Add a "daily limit" (or a flashcard review limit?) to the SRS settings

[fabd]

This was requested every once in a while:

I'm wondering if there's any news about this site getting a daily study limit that users would be able to set. I remember in the past the developer mentioned it. I'm getting swamped by kanji if I miss a day, and it's really overwhelming and off-putting.

I used to think this was unnecessary, but the way I see it now, is regardless what the "truth" is from the SRS point of view, the job of the software is to help the user.

The problem here is the software is implying something, which is not true. When cards are due, it is implied to the user, that all the cards must be reviewed on the day that they are due, in order to not forget them. Of course that is incorrect. For new cards it is important to review on time, but as the cards move up and get scheduled at greater intervals, the SRS can only approximate intervals based on past results, and it can never say "this is the day where you will forget this information". Not to mention that of course there is no binary "known" "forgotten" as memory is more complex.

Breakdown

Implementation consideration is whether to filter the cards at the backend or frontend?

To be consistent, if it says "50 cards", the bar chart needs to show only 50 due cards. This means probably first fetching the cards based on scheduling, trimming up based on daily setting, and then moving the remaining due cards to scheduled cards. At this point the bar chart on the front-end side can display the correct amount of due cards in each box, as per "daily limit". The front end can otherwise not do this since we can't say whether due cards in box 2, or box 4 etc. are the ones that should be trimmed out of the daily limit since the criteria is the scheduling.

• [ ] Implement a "daily limit" option in the Account Settings > Flashcards
• [ ] Implement the daily limit filtering of the SELECT results on the backend side, to keep the top N due cards for review (based on scheduling), then move any remaining due cards back to the "undue" pile (same box), so that the total of due cards showing in each box is below or equal to the daily limit setting.