I am kinda new to pull-ups and i am having a problem. So right now I can do 8 pull-ups in a row but if I try to do another set after some rest, I can only get 4 to 5 reps. Is there something I can change with my pull-up training?
How long are you resting between sets? The simple answer could very well be that you just need to rest longer between sets. As Dr. Mike Israetel explains in this video, there's no magic number for how long you need to rest.
https://youtu.be/0FZf6nv_aGg