How many cards a day is realistic?

For most people, 10–20 minutes of reviews a day is sustainable long-term. That's usually a few dozen due cards once your decks mature — the algorithm keeps the daily load roughly flat rather than letting it pile up.

Is spaced repetition only for language learning?

No. It works for anything fact-based you want to retain — vocabulary, medical and law material, exam prep, definitions, formulas, historical dates. It's less suited to skills you learn by doing, like coding or playing an instrument.

What's the difference between spaced repetition and active recall?

Active recall is the act of retrieving an answer from memory instead of rereading it. Spaced repetition is the schedule that decides when to do that retrieval. They're strongest together — see our active recall guide.

What is spaced repetition? A practical guide (with SM-2)

The forgetting curve

In the 1880s Hermann Ebbinghaus measured how fast he forgot newly learned material. The result — the "forgetting curve" — is steep: without review, you lose a large chunk of new information within a day, and most of it within a week.

The useful part is what happens when you review. Each time you successfully recall something, the curve flattens: you forget more slowly than before. Space those reviews out and the memory becomes durable — weeks, then months, then years.

Why spacing beats cramming

Cramming loads everything into one session. It feels productive because recall is easy while the material is fresh — but that ease is the problem. Memories that are easy to retrieve get little reinforcement. You pass tomorrow's quiz and forget it by next month.

Spacing forces retrieval when it's slightly hard — right at the edge of forgetting. That difficulty is the signal your brain uses to decide something is worth keeping. This is sometimes called "desirable difficulty": the mild struggle is the mechanism, not a side effect.

How the algorithm decides when to review

You don't have to schedule reviews by hand. Spaced-repetition software does it with an algorithm. The classic one is SM-2, the scheduler behind SuperMemo and Anki (and the one FlazhAI uses).

The idea is simple. Every card has an interval (days until the next review) and an ease factor (how quickly that interval grows). When a review comes due, you rate how well you knew it:

Got it easily → the interval multiplies and the card disappears for longer.
Got it after a struggle → the interval grows more slowly.
Forgot it → the interval resets to a day or two, and the card comes back soon.

How to actually use it

The whole system only works if you show up. A few habits make that easy:

Review daily, briefly. Ten focused minutes clearing today's due cards beats an hour once a week.
Keep cards atomic. One fact per card. "What year did X happen?" recalls cleanly; a paragraph does not.
Trust the rating. Be honest when you forget — that's how the schedule stays accurate.
Don't fear a backlog. Missed a few days? Do a short session and let the algorithm re-sort. Showing up beats catching up.

What is spaced repetition? A practical guide