Author claim " you can’t reinforce understanding.". But I can think of 2 counterexample: -A student that does't understand statistics or calculus then do a bunc

Author claim " you can’t reinforce understanding.". But I can think of 2 counterexample: -A student that does't understand statistics or calculus then do a bunch of exercise at home and suddenly understand the concept. -Or a student spend 1 hours memorizing all the geography location or date for an history class.