[veets]

In my experience, which is graduate level mathematics, spaced repetition is essential. Once you get beyond basic mathematics and algebra, recalling and understanding concepts and definitions is essential. This is true at the calculus level where you need to remember things like the chain rule, integration by parts, various theorems, etc. But it is even more true at the higher levels of mathematics where there are many more theorems, lemmas, and definitions to remember. I find that at that level, just having a huge depth of recall for definitions alone is incredibly useful. If you remember enough definitions you can start to piece things together. If you can recall theorems, lemmas, and some key proofs you can achieve quite a bit.