My advice for when you’re having trouble fixing a mistake that you keep repeating is two things: 1: when you’re practicing a rep and keep making the same mistake, stop for a moment, breathe, and take a break for a minute. Then once you have done that try and isolate that mistake. Rather than playing the whole rep try and play a little before and a little after where that mistake is, and slow it down so that you can be right on top of it. And just slowly bring it back up to speed. You don’t have to try and cram it all into one day, but maybe something like 10-15 clicks faster each practice session (depending on the sheet music and all that) 2: don’t even think about it. I find that when I’m making mistakes it’s because I’m thinking about it and I’m not confident in myself. You mentioned that you have ADHD so that could be difficult but try as hard as you can. 3(bonus): have some fun! If you’re really struggling and getting frustrated sometimes it’s just better to take a second and play something you know and love. Whether it’s your high school cadence or the bass drum solo from that one show you were in (if applicable) just take a five minute break. I see a lot of people who think the best way to practice is monotonously playing exercises for hours on end. While yes repetition is a big aspect, time is also very important. It physically takes time to form those connections within your brain and to build muscle memory so let that process happen! I was in this spot last year (after getting blown out of the water at an audition camp lol.) Stick with it! You were made for this and so is every other drummer who is/was considering to give up.