To be clear, I am by no means saying anything contradictory to what Mathwonk is saying. Every summer I go back and review material and learn new material on my own. This is of paramount importance, to be sure.
BUT my difference is that you have to do this in addition to getting good grades. I have never said, (though most people in here are implying I said), that it is ok to get the grades and not know what your doing. I don't care how you learn, what school you go to, or any other particulars. If you go to a school that does not require things from you like HW in order to pass, it stinks. Good schools are not places where you just sit through great lectures and take exams. Good schools give you lots of work to keep you busy in the process. Now, if you want to moan and groan about this because your lazy, well then I simply DONT CARE. Like I said before, I am glad I don't go to your school if that's the case.