Never Forget What You Studied: The SM-2 Spaced-Repetition Revision Engine | NEETPGAI
Never Forget What You Studied: The SM-2 Spaced-Repetition Revision Engine
How NEETPGAI's /revision engine uses the SM-2 algorithm — ease factor 2.50, a 3, 7, 14, 30, 60-day ladder, zero setup — to resurface every NEET PG question you got wrong. Free for all users.
NEETPGAI Editorial TeamPublished 21 May 202613 min read
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Never Forget What You Studied: The SM-2 Spaced-Repetition Revision Engine for NEET PG
Quick Answer
The NEETPGAI revision engine uses the SM-2 spaced-repetition algorithm to bring every NEET PG question you got wrong back at the moment you are about to forget it — automatically. Here is how it works in 5 points:
Zero setup — every MCQ you answer wrong anywhere on the platform becomes a review card. No deck building, unlike Anki's 50+ hours of manual work.
SM-2 math — each card carries an ease factor (default 2.50, floor 1.30); a repeat wrong answer decays it by 0.20 and resets the schedule to tomorrow.
Interval ladder — correct re-attempts climb a fixed ladder of 3, 7, 14, 30, then 60 days, then switch to classic SM-2 multiplication.
One queue across 19 subjects — the Due Reviews tab at /revision pools due cards from a large approved-MCQ bank, oldest-due first.
Free for everyone — the revision engine is free for all registered users, with no daily cap.
The problem: you forget faster than you re-study
Forgetting is the default state of the human brain, and NEET PG punishes it harder than almost any exam in the world. You study Pharmacology in month one — antimicrobial spectra, adverse-effect profiles, the cytochrome P450 inducers and inhibitors. By the time you sit a grand mock test in month seven, half of it is gone. You re-read the same notes, feel the dull recognition of "I knew this," and forget it again two weeks later.
This is the Ebbinghaus forgetting curve in action: without active reinforcement, memory of new material decays steeply within the first 24 hours and keeps falling for weeks. For an exam testing recall across 19 subjects and well over a thousand discrete topics, passive re-reading is a leaking bucket. The questions you got wrong in January are exactly the ones you will get wrong again in August — unless something forces you to confront them on a schedule built around your own forgetting.
The honest fix is spaced repetition. The practical problem is that doing it by hand is brutal. Building Anki decks for all 19 subjects takes dozens of hours before you review a single card, and most students abandon the deck by week three. The science is settled; the friction is what kills it.
How the SM-2 revision engine solves it
The NEETPGAI revision engine is an automated spaced-repetition system that schedules your missed questions using the SM-2 algorithm — the same 1987 SuperMemo formula that powers Anki — with zero manual card building. It lives at /revision, and it turns your own practice mistakes into a self-organizing review queue.
Here is the mechanism, exactly as implemented. The moment you answer a question wrong — in practice, a mock test, PYQ practice, or the daily challenge — the engine seeds a review card scheduled 24 hours out. Each card carries an ease factor, which starts at the SM-2 default of 2.50. From there:
Get it right on review → the card climbs a fixed interval ladder: 3 days → 7 → 14 → 30 → 60. From the sixth correct repetition onward, it switches to classic SM-2, multiplying the previous interval by the ease factor.
Get it wrong again → the interval resets to 1 day (the card returns tomorrow) and the ease factor decays by 0.20, down to a hard floor of 1.30. A genuinely hard question keeps returning frequently but never vanishes.
The design choice that matters: only wrong answers seed cards. A first-time correct answer is deliberately a no-op. Your review time is spent entirely on what you actually got wrong — not on padding the queue with material you already know. This is the opposite of a pre-made Anki deck, where you grind through thousands of cards regardless of whether you ever struggled with them.
The /revision Due Reviews queue surfaces every card whose SM-2 schedule has come due, oldest-due first, across all 19 subjects — with one-tap filters for subject, image-based questions, and previously-missed real previous-year questions.
Proof: the bank and breadth behind the engine
The revision engine is only as good as the question bank that feeds it, and NEETPGAI's numbers are verifiable, not aspirational. Every figure below is drawn from the live proof ledger as of 30 May 2026.
31,000+ approved MCQs are live and student-facing — every one of them is eligible to become a review card the moment you get it wrong.
19 subjects are covered, from Anatomy and Pharmacology through Radiology, Psychiatry, and Dermatology, so the Due Reviews queue can span your entire prep, not a handful of subjects.
1,000+ exam topics are mapped across those subjects, which means a missed question is tagged precisely enough for subject-level filtering to actually be useful.
1,679 real NEET-PG previous-year questions (spanning 2018 to 2025) sit inside the same bank, each dual-AI verified by Claude Haiku 4.5 and Gemini 2.5 Flash and SME-reviewed — so your PYQ-only review queue draws only from authentic exam content.
And the part that matters most for adoption: the revision engine, the full 31,000+ bank, real PYQs, mock tests, and analytics are free for every registered user. Only three features are paid — the AI Tutor, the AI MCQ Generator, and the OSCE Clinical Case Simulator. Spaced repetition is not behind a paywall.
Benchmark: vs paper flashcards, Anki, and video qbanks
The revision engine competes with three things students already use to review: paper flashcards, hand-built Anki decks, and the "rapid revision" modules inside video platforms. The honest comparison is below.
Two points are worth making precisely. First, Anki and NEETPGAI run the same core algorithm. Anki's scheduler is built on SM-2 from SuperMemo (SuperMemo SM-2 specification), and so is the NEETPGAI revision engine. The difference is not the math — it is that NEETPGAI removes the deck-building tax entirely and binds the schedule to a curated NEET-PG bank, while Anki gives you total control at the price of hours of setup.
Second, video-platform revision is not spaced repetition. Marrow- and PrepLadder-style rapid-revision modules are excellent for fast theory consolidation, but they are linear playlists, not per-question adaptive schedules — everyone gets the same sequence regardless of what they personally keep getting wrong. They complement the revision engine rather than replace it. (We keep this comparison qualitative because those platforms publish no per-question scheduling spec to benchmark a number against.)
Using the revision engine is a five-step loop that runs itself once you start practicing. These steps mirror the structured walkthrough below.
Practice normally. Attempt MCQs anywhere — practice mode, mock tests, PYQ practice, or the daily challenge. Every wrong answer is auto-seeded as a review card scheduled 24 hours out. You build nothing.
Open the Due Reviews queue. Go to /revision. The Due Reviews tab lists every card whose next-review date has arrived, oldest-due first, pooled across all 19 subjects.
Re-attempt each due question. Answer it again. Correct advances the ladder (3 → 7 → 14 → 30 → 60 days); wrong resets the interval to one day and decays the ease factor by 0.20.
Filter when you need to drill. Narrow the queue to a single subject, to image-based questions, or to previously-missed real PYQs. Use this in the final weeks to attack weak subjects head-on.
Review daily, never skip. Treat the queue as a daily non-negotiable. A skipped day stacks tomorrow's queue; a consistent daily pass keeps every card climbing toward permanent recall.
Want to seed your first review cards right now? Practice a few MCQs below — anything you miss enters the SM-2 queue automatically.
Who it's for
The revision engine fits any NEET PG aspirant who practices MCQs, but it pays off differently depending on where you are.
Early-phase students (9+ months out): This is your highest-leverage user group. Start now and a card seeded today can climb the full ladder to a 60-day interval and beyond before exam day, reaching genuinely permanent recall. Time is the multiplier SM-2 needs.
Repeaters and second attempters: You already know which subjects betray you. Use the subject and PYQ-only filters to rebuild retention on your historical weak areas instead of re-reading entire subjects from scratch.
Final-90-days crammers: You will not get the full compounding effect, but the queue still forces you onto your actual mistakes daily — far more efficient than passive revision. Lean on the image-only and PYQ-only filters to maximize yield per minute.
Anki loyalists: If you already run a polished Anki workflow, keep it. The revision engine is for everyone who tried Anki, drowned in deck building, and quit — it gives you the same SM-2 schedule with none of the setup.
Frequently Asked Questions
What is the SM-2 algorithm and how does NEETPGAI use it?
SM-2 is the spaced-repetition algorithm SuperMemo introduced in 1987 and the same one Anki uses by default. It schedules each item with an ease factor and an expanding interval so you review just before you would forget. NEETPGAI's /revision engine implements SM-2 with a 2.50 default ease factor, a 1.30 floor, and a fixed early-interval ladder of 3, 7, 14, 30, then 60 days.
Do I have to build flashcards to use the revision engine?
No. The revision engine is fully automatic. Every MCQ you answer incorrectly anywhere on NEETPGAI is seeded as a review card with no setup. This is the core difference from Anki, where you build and tag decks by hand across 19 subjects. You practice, the engine schedules.
Is the spaced-repetition revision engine free?
Yes. The /revision engine, the full approved-MCQ bank, real previous-year questions, mock tests, and analytics are free for every registered user with no daily cap. Only three features are paid: the AI Tutor, the AI MCQ Generator, and the OSCE Clinical Case Simulator.
What happens to a question when I get it wrong again?
On a repeat wrong answer the engine resets the interval to one day, drops the ease factor by 0.20, and schedules the card for tomorrow. The ease factor cannot fall below 1.30, so a stubbornly hard question keeps returning frequently but never disappears entirely. This is SM-2's way of forcing extra repetitions on your weakest items.
How is this different from the Anki decks medical students use?
Anki and NEETPGAI both run SM-2. The difference is friction and content. Anki needs 50+ hours of manual deck building and pre-made medical decks still need editing. NEETPGAI seeds cards automatically from a MCQ bank covering 19 subjects, so there is zero setup. Choose Anki for total customization, the revision engine for zero-effort automated review.
Do correct answers create review cards too?
No. Only wrong answers seed cards, matching the principle that you should spend review time on what you actually got wrong. A first-time correct answer is a no-op. Once a card exists, a correct answer advances it up the interval ladder; a wrong answer pulls it back to a one-day interval.
What are the exact review intervals?
After a card is created, each correct re-attempt moves it up a fixed ladder for the first five repetitions: 3 days, then 7, 14, 30, and 60 days. From the sixth correct repetition onward the engine switches to classic SM-2, multiplying the previous interval by the ease factor (default 2.50). A wrong answer at any stage resets the interval to one day.
Can I revise only my missed previous-year questions?
Yes. The Due Reviews queue includes a PYQ-only filter that restricts the queue to promoted real NEET-PG previous-year questions you previously got wrong. NEETPGAI has 1,679 real PYQs spanning 2018 to 2025, each dual-AI verified and SME-reviewed, so your PYQ revision draws only from authentic exam questions.
How many reviews per day should I expect?
It depends on how much you practice and how often you are wrong, since only wrong answers seed cards. A heavy practice phase early on can build a queue of 50 to 150 due cards per day. The queue self-limits as you answer correctly and intervals stretch out, so disciplined daily review keeps it manageable through to exam day.
Does the revision engine cover image-based and clinical questions?
Yes. Any approved question you get wrong can become a review card, including image-based questions across X-ray, CT, MRI, histopathology, ECG, clinical photo, and fundoscopy. The Due Reviews queue has an image-only filter so you can drill visual recognition separately from text MCQs in the final weeks.
When in my prep should I start using spaced repetition?
As early as possible. SM-2's compounding only works with time: a card seeded in month one can climb the full ladder to a 60-day interval and beyond before exam day, while a card seeded in the final month gets only one or two repetitions. Start practicing now, let the engine seed cards from day one, and clear the Due Reviews queue daily.
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Written by: NEETPGAI Editorial Team, Medical Educators
Last reviewed: 30 May 2026
The NEETPGAI Editorial Team builds product-led guides to the platform's revision, analytics, and practice engines for NEET PG aspirants. This article documents the live /revision spaced-repetition engine as implemented on the platform.
