Hello all: I am currently working through Richard Courant's Calculus. There are some problems which I just cannot do, either because it is extremely difficult or very time consuming. However, I have this obsession in wanting to do every single problem. Would it make more sense to move on to more important topics, read every chapter, and then do problems of your own liking? Do I have to do everything linearly? Is this a good way to study and master calculus? Any advice is appreciated. Thanks!