When you do revision, do not revise in large chunks. Break up your revision into time intervals which makes sense of how hard the topics you are learning actually are. Revise more hours for the topics you are struggling with and try not to revise as much the content that you already know. A technique I utilised was that I said that I was going to revise 2 hours for a hard topic and approximately 30-45 minutes for a simple one and I would always have breaks in between lasting about 30 minutes to an hour. Revising long hours is really bad because it will burn your brain out. Allocate days where you just rest and do no work at all because the best way to revise like many things is through rest and recovery. Do a lot of work one day and then rest and chill the next. Like I said before, don’t revise too long but at the same time, don’t slack off too much. You need to find the balance between work and free time to be most efficient at revision and it is when you find this balance that you will get the best out of yourselves.