I was fortunate in that my teacher for the supported choice questions gave us a booklet with every question from edexcel, all ordered into individual categories. E.g. Oligopolies, contest able markets etc. With a mark scheme attached at the back. You get so used to the questions and the repetitive order that after a while definitions and formulas become second nature. I don't have the booklet anymore

it may have been recycled.
As for the essays unit 3 was very much having knowledge and applying it and understanding why markets run the way they do. If you understand the supported choice you'll be fine with your unit 3 essay as it's just an expansion of the topics.
Unit 4 was really just bulky writing. Learn or better yet ask how many marks you get for each question for data (usually 2-4) analysis (2-8) and evaluation (2-8) don't take my marks as the actual amount as I do not know for sure.
I got a book and re wrote my notes abbreviated. I didn't waste time on stuff I was confident I knew and to be honest I did very few essays, I think a lot of success came from criticism from my teacher, and learning how economics happens. It is just a chain or if you like dominoes, one change precedes the next

ultimately you've just gotta find your own way. I knew I could remember quite a lot of stuff with little practice, I'm fortunate like that, but there were certainly kids who knew more that blew it through timing, or not making it clear enough or even overthinking.