Some people are incredibly lucky and have memories that retain pretty much everything they read, on top of a lot of natural intelligence. This combination means that GCSEs which on the whole have very little content are simple, and no work is required, if they are even more lucky then that memory is semi photographic, so they can remember the actual pages and stuff like that of reading, even A Levels become pretty simple to pass, provided their intelligence suffices to understand the actual concepts that they need to understand, so it is possible to do well at A level with little to no revision too, as it is just a case of understanding the concepts and being able to memorise ways to apply them. At degree level it becomes impossible due to the format; there is a lot of content and most of it is only touched upon, and none covered in enough depth that the revision isn't needed. In fact revision is necessary here even for those lucky people who up the point of their degree have done pretty much no extra work/revision.