Prior to the new exam format we had exams when ever the professor wanted to have them. As a result we had exams every week. No one was ever coming to class because they would skip and cram for the next exam. A friend would try and sign them in so they would maintain the 80% attendence.
In the end no-one was learning anything because of all the craming, and the sign in sheet became a real point of contention for both faculty and students. The new system was put inplace to try and cut down on those problems.