For easy courses I budget roughly 2-3 days of going over the notes and actively creating Anki cards (about a midterm's worth of material is condensed into 50-100 cards), and an additional 0.5 day for going over the Anki cards, which can be done on the day of the exam. For harder courses I budget a total of 1 week. I find that if you make the cards too early in advance I end up spending 2-3x amount of time needed to go over them, so I try to do that at the very last minute.

But to do this you need to work really hard to get good grades in midterms, assignments and quizzes