Very cool site! I always wondered how you were supposed to schedule Leitner boxes manually. Somewhat related, https://kanji.koohii.com/ https://kanji.koohii.c

Very cool site! I always wondered how you were supposed to schedule Leitner boxes manually. Somewhat related, https://kanji.koohii.com/ https://kanji.koohii.com/ uses online Leitner boxes to learn how to write all the 2000+ official commonly-used Kanji in Japanese. But I believe the timing of when the cards come due is based on when they go into a box + a certain amount of time, instead of reviewing an entire box in one day (which it can do easily since it's software). It's nice to see the stacks in each (virtual) box progress over time.