"I never even need to look at the book while studying for a test. If I have paid attention in class every day and if I take good notes, then all I need to do before a test is study my notes so all those ideas are fresh in my brain." —Liz L., student
When students are learning effectively, cramming for tests becomes unnecessary. By the time the test happens, they already know the material. Reviewing for the test means double-checking for possible weak areas, polishing the learning one more time, and getting an overview of what has been learned. The test itself becomes a check-up.
How students prepare for tests is an excellent indicator of how well the culture of learning is functioning. When the process is working well, learning is continuous and the test is just a snapshot of the state of that process.
Similarly, preparing for a semester exam is an opportunity to give the student an overview on what he has learned and let him identify areas that need more work. However, if real learning has been taking place, preparing for an exam should not require extensive practice.
If we imagine a spectrum stretching from memorizing and regurgitating on tests on the one hand, and true, deep learning on the other, preparing for an exam is an excellent opportunity for students to see where they are on that scale.