and i'm not sure how everyone else studies, but i find that for most subjects, the notes they give us contain everything we need to know for the exams, and that reading a textbook is just for getting a different perspective or method of presentation of the content that is already covered in the notes.
though admittedly, there are good notes and bad notes...
you might want to start checking out online resources too, can be quite interesting, if irrelevant reads occasionally, the science journal websites. (all free access, so don't pay for anything!)