Besides the theory there are a lot of small technical details that must be learned so well that you can recall them almost instantaneously, such as the trigonometric identities... put one part of the identity on one side of a 3 x 5 card and the other part on the other side. Using these flash cards you can, in the odd moments of your daily life, learn the mechanical parts of the course.... for this kind of low-level material many short learning sessions are much more efficient than a few long, intense ones; but this is not necessarily true for larger ideas.... most students will not use such trivial devices as flash cards; it seems to be beneath their dignity. They suffer accordingly.
Methods of Mathematics Applied to Calculus, Probability, and Statistics (1985)