Designed and made these for my son and daughter when studying for exams. They form a set of boxes to store flashcards. To start with all the cards are in the daily review box. They are reviewed daily When they are confident with the cards they move them to bi-daily and see them every 2 days. If they falter, the the card moves back to daily, when confident to tri daily then weekly. This way most time is spent reviewing the cards they are least confident about.

Seemed to work.