I believe this is a really good thing to do because it makes something so big and daunting to be really quite relaxed in terms of your revision. By doing revision this way, you won’t avoid it and you’ll make sure that you stay on top of your work by doing it bit by bit throughout the year rather than having no revision plan for the year and just cramming revision near the end. For some subjects, breaking subjects down into sections is really easy like maths for instance. All you have to do is just revise as normal but revise one topic on one day and then another topic on another day and so on. The topics are basically handed for you in maths so it shouldn’t be too difficult for math students to break your revision down into subjects. For other students, I would look at a textbook which is probably given to you and see if they have cut down your subject into sub-sections. If you have a textbook and this is done for you, then that’s great. If not, then don’t worry. Just ask the teacher which work is attributed to which topic and then go on from there. If you’re too shy to ask the teacher or their advice is sh** (you can make out for yourselves what the asterisks are), then make topics yourself that make sense to you. Even if it’s not right, as long as it works for you, that’s the main thing.