Interesting. I think I've read research suggesting that answering questions is significantly better for learning than just reading material (similar to how Anki asks you questions instead of just telling you things).

Val at CFAR likes to make the point that if you look at what students in a typical math class are actually practicing during class, they are practicing copying off the blackboard. In the same way maybe what most people are "actually practicing" when they do math homework is flipping though the textbook until they find an example problem that looks analogous to the one they're working on and imitating the structure of the example problem solution in order to do their homework.