I basically only put two things in there: "Prove X" and my ordinary problems. Then I'd just do that. Those cards usually took at least a minute apiece, but I got really good at abstract algebra, at least when compared to similarly skilled peers. Mind you, I have always been good (perfect SAT score) but not great (never scouted for Putnam) at math.
Contrary to what you might think, memorizing definitions is less useful (though not totally useless) than memorizing the proofs of theorems which rely upon those definitions.
I would almost certainly go back to doing this if I ever want for a master's degree with a math class again. The idea crosses my mind every now and then to do it with linear algebra, which counterintuitively isn't actually a prerequisite for or all that similar to abstract algebra.
Not affiliated but 3 months in and I feel my math foundations are finally solidifying into something that will allow me to build into areas previously out of reach
I tried it ones to reinforce chess openings, but I never developed the momentum to keep it up. I think I was—and still am—lacking the ability to visualize the moves in my head from the algebraic notation on the cards.
