I think there are two kinds of exercises, one is the exercises after learning new knowledge, such as the usual exercises, and the other is the exercises after reviewing, such as the final review exercises.

The first question can test whether you have learned the corresponding knowledge points. If you can do it, it means that you have learned the corresponding knowledge points, which is of course good. If you can't do it, it means that you haven't learned the corresponding knowledge points well, so you can go back and scholars can fill your learning loopholes.

The second question is mainly to help you consolidate your grasp of the corresponding knowledge points and fill the corresponding knowledge gaps.

This is just my personal opinion. Based on the above points, I like doing math problems very much.