I have a bad habit of trying to objectively measure myself and my understanding. One of the ways I do this is by saying to myself "I only understand X after I have read the entire chapter in this book on X" or "I can start doing a problem on X after I have read all about X." I do this because it generally guarantees that I haven't missed something important; that I'm not stuck on something that's obvious to everybody else. It's also something external that I can point to to justify my ignorance. Like, if I didn't know something, I could say "Well if that's important, then why didn't this author mention it in this entire chapter?"
A lot of my peers don't do this. I think most of them pick up just enough from lecture to do the assignments. I'm really starting to wish I was like that because this way of learning is seriously failing. It's starting to take a tremendous amount of time and I'm under time constraints. But it bothers the hell out of me if I can't first get all the facts down.
And actually I did this last semester with one class because it was simply unfeasible to follow along with the book. When I look back I feel somewhat bad about it because the subject truly interested me.
- So how should I balance learning and solving assignments during coursework? On one hand, I spend a lot of time with the books as there's a lot of stuff to learn and it helps to know all the facts and the motivation behind the ideas, as they can be enlightening. On the other hand, it leaves no time and my performance in school could be better if I focused more time on doing the assignments.
I'm not sure whether this is on topic, but I'll answer anyway.
It looks like you have time management problems. Sure, it is interesting to learn as much as possible about a topic and study it deeply, but ultimately, you have assignments and exams to complete. To a large degree you should be optimizing your time usage to do as well as possible in these.
One way to determine whether you have learned enough is to attempt a lot of exercises. See how far you get with them. If you cannot do them, then this helps identify holes in your knowledge. Read about that particular topic. If there are things you don't understand while learning about the topic, work backwards and try to fill in those gaps.