Revising isnt always how you think it needs to be.
It doesn't need to be pouring over every topic in every subject for hours in end of reading text books.
My ds weakest subject was English.
He had revision guides etc but he learns best by talking.
So we use to do mind map on white board. School will tell them what they need to know.
So for Macbeth for example I'd write characters - he'd name them - and I'd write them down.
I'd then ask for a quote for each and write them down. Then I'd ask him significance of quote and write it down. Once complete, photograph and print. We'd then expand on this next time and add to it.
Ds is also a swimmer and would spend whole weekends once a month competing.
Between races and lunchtimes etc he'd go on bbc bite size. Read and answer the questions.
Best thing we had was checklists from school of all topics and knowledge criteria for each topic.
When ds was sound on something we highlighted it. We focussed on the things he wasn't sound on.
I've always believed it's unmotivating to spend hours reading a topic you're sure of as you naturally start thinking of all the others things you could have been doing instead.
By grasping something new it's motivating and revision is interesting if you feel a sense of achievement.
Mh ds did 2 hours a day during Xmas. He choose of all at once of split into 2 sessions.
He also never did more than 30 minutes revision on any one subject at any time.
He was going to do 3 hrs at Easter and 4 in May. But covid changed everything!