Also getting to know how the professor thinks helps you anticipate which material to focus on and even helps anticipate questions for a test. I had a professor literally call out the whole class about not going to his office hours and not getting to know him. He said its to the students advantage to know how i think. Worked well for me because i knew exactly how to write papers for him. Also he was a very smart guy so i enjoyed talking to him and ended up grabbing a beer with him at end of semester.