if that is the case then try the questions and mark your work and see which question you went wrong on and then focus your revision on the part of the content then this means you will only need to look at the content your weak at, and yea i also started my GCSE's in year 9, plus i didn't do much revision in year 10, i started properly revising in January like 6 or 7 moths before the GCSE's, as many people start revising in year 10 thats good but only do a little bit at a time, dont burn your self out.
The method used to revise content is spaced repetition literally everyone laughs at me when i say this even my teachers are like thats not a good method but i humble them when it comes to the test, what i do is read over the content i want to learn literally just read over it while trying to understand the content like why that particular thing happens then it will be easier to remember and then i wait a few days and come back to the content again and read it again and come back in a week and read again, and every time i come back to the content my brain will be like " oh he is coming back to the content again this must be something i need to remember and then stores it in your long term memory" and the next time you come to read it again you will feel like you have photographic memory as your brain literally just goes and fetches the info form your long term memory. And then i do a lot of exam question on PMT there is so many on there you literally wont run out ! on every topic and the sub sections within each topic ! (
https://www.physicsandmathstutor.com/)
This method many not work for you but, it is just there as a powerful method i used !
I literally still use this method for my a level i could literally read out the first 20 pages of my A level biology notes out to without looking at it ones, and i know exactly where all the diagrams are on each page and like what each label on the diagrams are because this method literally made me have photograph of my notes in my head !
hope that helps!☺️
anything else feel free to ask!