Comment by Zarath

It seems like you'd be surprised to learn that the ability to recall and utilize something under constraints is highly indicative of a person's understanding of that material. The kids who "memorize formulas" aren't the ones getting straight A's. The ones who understand and grasp the material are the ones who will have no trouble performing under pressure, because if they forget something, they can recall it using their knowledge structures.

E.g. Say I forgot the formula for Simpson's Rule on a test, but remember that it had to do with approximating integrals with trapezoids. Someone who thoroughly understands the course material could re-derive this formula in under 5 minutes if they had forgotten.