Why isn't FSRS the default scheduler?

Why isn’t FSRS the default scheduler?


Because it will take time to iron out the integration kinks, and it doesn’t currently work for everyone (e.g. people who fail cards with the hard button instead of again).


Is there anything wrong with always pressing “Hard”?

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Yes, there is.

When you get the answer wrong, the correct button to press is “Again.” That’s the only one that gives either scheduling algorithm the correct information.


If you press Hard all the time, retention is 100%.
If you ever press Fail, it has to be at least as low a rating as Hard.

Is there documentation somewhere on how to use each button? I read entire manual when I first started anki (albeit years ago now) and it was never really explained how to use each button. I just assumed you should use it however works best for you. Specifically, what are hard and easy for? Again and good are easy to understand. I just saw hard as again lite and easy as good on steroids.

There are definitions for SM2. It’s not as clear with FSRS, but basically Hard means retained (counts into the retention rate), but worse than Good (usually less easy, not with a mistake).


You’re not alone! As dae said, that’s the biggest reason why an individual user might need to put off enabling FSRS. Hard should really be thought of based on its relationship to Good, not Again.

I’ve found this helpful for conceptualizing what each grade means – Studying - Anki Manual. I think about how long the delay was since the last time I saw the card. To be clear, this is meant as a gut-check about how it felt answering – not a time to be counting days and worrying about the algorithms. So if the time-intervals displayed on the buttons are a distraction – turn them off.

Again = incorrect/inadequate answer
Hard = that delay was too long (I really had to stretch for the answer)
Good = that delay was about right
Easy = that delay was too short (it took no effort to answer)


The reason why I thought like that is that. Because by default anki lapses have 0% of the original interval. It seemed like I would have a giant workload if used again all the time.

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Again = did not recall.

Hard = recalled, but with difficulty.

Good = recalled without terrible ease or difficulty.

Easy = recalled with ease.

They are fairly self-explanatory.


I think the contradiction in that idea is that instead of allowing a card that you’ve forgotten to lapse – you’re giving it a longer interval [Hard means current interval * “Hard interval” modifer, which is 1.2 by default]. That seems crazy when you already know that the current interval was too long.

Yes, lapsed cards (under the SM-2 algorithm) return to relearning steps and graduating interval – but that’s because you need to study them more. :sweat_smile: That seems like the right reason to increase your workload. I would think by not lapsing them, you’re making even more work for yourself, by leaving these cards out there, with rapidly descending ease, and no chance to ever re-learn them.

Not even fsrs gives you 0% of the previous interval . I think it was a mistake on anki part


It wasn’t a mistake. It works exactly as designed, and follows the SM-2 algorithm on which it was based (What spaced repetition algorithm does Anki use? - Frequently Asked Questions) by default (although it can be modified).



While preserving part of the interval may seem to make sense, SuperMemo has observed that preserving part of the delay can actually be counter-productive. For this reason, we recommend you leave it on the default setting.


it causes people to use hard instead of again. It’s a bad design decision


It isn’t what causes people to use Hard instead of Again. The cause of that is people trying to use a spaced-repetition system/algorithm without understanding how it works or trusting that it does work.

Anki (and the sound SRS algorithms on which it is based) shouldn’t be redesigned for the benefit of folks who aren’t going to trust spaced-repetition anyway.


People not wanting to have their new interval be 0% of their last has nothing do with people not trusting srs.

And saying anki shouldn’t adapt to people who don’t trust srs implies. That anki should ignore the people who never use again and move to fsrs


We’ve wandered pretty far from the orginal topic of this thread, so I guess we’ll have to agree to disagree.


To be fair, if you forget something, it is hard. So I can see why people would hit “Hard.” “Again” should be named “Forgot” or something. This is not explained anywhere in the app.


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