The use of case studies is often essential in geography exams as they help create structure in a long answer question and also display your knowledge of specific examples in reference to any facts you may be discussing. The best way to revise case studies e.g. different locations of plate boundaries around the world, could be to group them into categories such as: destructive, constructive, conservative and collision. This categorisation would allow you to pin point key facts about each group which could then be applied to specific case studies that you choose to write about.
Another method could be to draw case studies onto a map and annotate them as a more visual way of revising. This would aid with meorising both their locations, and information specific to each study; which in an exam may be easier to remember if you are a visual learner. It is also important to remember that often fewer case studies but in more detail, is more useful than writing about a large number of case studies which you do not have as many specific ideas or facts about, try and be as concise and to the point as you can to get across your argument.