Knowledge that is primarily conceptual (like almost all of math) generally does not benefit from spaced repetition. The learning involved is understanding -- a new concept may be hard to understand in the first place, but once you get it, you don't really forget it. Or you just need a super-quick refresher if you haven't touched it for a few months.
While knowledge that is primarily arbitrary-factual is the perfect candidate for spaced repetition -- mainly things like vocabulary, medical terms, and so forth. Just associating a largely arbitrary name for something. And indeed they are mostly useful for learning for exams. E.g. I used it to learn Chinese characters and could never have passed Chinese class otherwise. But on the other hand when I actually lived in another country that speaks a different language, spaced repetition isn't much of a help -- you learn vocab just by absorbing it day-to-day, like a kid does.
Some ways in which it's different:
- Dependencies are core to the system. For example, if I am learning a music piece, I want to start by learning small sections and only move on to larger sections when I am good enough at the small stuff, eventually ending with a final exercise that tests my performance of the whole piece. A lot of knowledge/skills follow that pattern, but I couldn't find a way to make Anki or SuperMemo understand this.
- It's meant for both memorizing stuff and practicing exercises. I have tested it with your exact example (math problems from textbooks). It works fairly well, but it's at a very early stage (you can look around at https://github.com/trane-project/trane-math, but it still needs a readme). So it's doing the same thing as the students you mentioned. The difference is that the scheduling is done automatically. Review of existing problems and addition of new ones happen without requiring planning or tracking from the student.
- There's an emphasis on generating the flashcards as text files, so they can be shared. I don't understand why people insist of remaking their own flascards every time. If someone wishes to learn guitar, for example, it's my hope they just download some courses and start learning without spending any time redoing flashcards. This design choice probably makes it harder to write the flascards, but it balances out once the flashcards are done and can be passed around.
Things I use frequently I already pick up through repeated use, things that I never use eventually falls out.
But things that are somewhat relevant about that I find myself googling more than twice is a good candidate to Anki.
Isn't it the case that only minority of students uses this software or flashcards in general anyway? I mean, of course it is possible to succeed without it, because overwhelming majority of students/learners are not using it.
What pushed you to make the switch? Was it Incremental Reading, or some other feature/reason?
Just under a month ago, I read about 'math academy' here on HN. One thing it does is sort of what it sounds like you envisage: surfacing exercises relating to concepts you might be about to forget.
As a caveat, sometimes it can be hard to do this. If I randomly pick textbook problems, I have no guarantee that the new material will review the old.