When I'm taking courses in Calculus I & II, and Linear Algebra, the lecturers are always telling us to do as many exercises as possible. But when it comes to practical situation, I realize it takes so much time on exercises especially calculation parts.
So I'm thinking about whether it's really necessary, because I found that I love proof exercises mostly, with that, I could think more, and make connections among many theorems, to see how they are related and what it really means. But for many 'calculation' exercises（say 400-500 problems for each chapter totally） I realize for most of them are just substituting the data into the formulas, and doing calculations are somehow less helpful in understanding compared with proof problems or just read & re-read text part and thinking.
So in this case, I want to ensure that whether or not what I'm doing is suitable, because lots of people around told me that it's dangerous. Thus, I want to know more advices or explanations. （It's somehow impossible to focus both proof and calculation as much as possible, and I've enjoyed and benefited from the former but not latter one.）