You can memorize ten or even hundred times faster (compared to cramming) if you review learned material at spaced intervals. The spaced repetition method is most appropriate for small, particular facts you need to recall quickly, such as terms, or frequently used formulas. Never try to memorize what you don’t understand in mathematics. For bodies of facts, such as multiplication, it’s best to use math patterns rather than direct memorization.
You can arrange spaced repetition with low-tech means, with multiple boxes of cards, but it’s very cumbersome to manage. Modern software is much better for the management, such as my favorite free and open tool, Anki.