In an ideal world, students wouldn't need to study so much. If we reviewed our notes each week, actually did our assigned writing, and put a little more effort into class discussions, there would be less need to cram at the last moment. But realistically, few students review each week, do ALL assigned reading, etc.
Of course, some of us can get by not doing the above and still not studying
It depends on your personal capabilities and interest level in the course. It also has a lot to do with teaching style and whether your professor is putting the material into words you can really understand and remember.