[0_gravitas]

Repetition to wire up thought processes and logic (why do X instead of Y) != Arbitrary memorization of trivia (X formula or Y proof)

The difference between learning X and understanding X

[Ekaros]

Training the common tools and pattern recognition for things algebra. At higher level you really need to have a repertoire of various tricks to apply to integrals and derivatives... I never properly learned these for University level.

Often the problems had some trick that you had to apply to solve it. And without knowing those certain tricks from routine finding right solution was pretty hard.