We all work according to our own strategies and we all study according to our own strategies. Sometimes we spend a lot of energy and clock on small portions which is unnecessary. You need to realize that time is limited and you also have to save time for more big and important sections. Then you need to make time for revisions too. So, try working as a smarter one, not a harder one. Understand that sometimes you have very less time to sum up everything and study it. Therefore make a list of all the small portions you got out of the subjects and start reading them. Realize that you have to manage time and your whole syllabus so, start with the small portions and study them at one go. Move through them so thoroughly that if you get no time to revise them it shall be okay by not creating much difference. Well this strategy helps a lot of people.