Personally, I think that revision should be done throughout the course.
First of all, it is more effective in terms of remembering the course for a long time. Revision at the end of a course may let people pass the exams better but they will forget the material faster. I remember we had revisions during my history course and I remember much of the material I studied even now. As for geography, we had the revision just before the exams and I forgot almost everything.
Second, revisions during the course make students repeat the materials more often, which makes one understand the information better. My schoolmates say the same thing, “as soon as we have a few revisions during the course, we remember its material forever”.
So that’s why I think that revision during the course is better.