for me i used to do like 6 planche push ups to 3 presses to 2 secs of hold negatives, archer push ups to press to negative, wide planche press to negative, etc this march. but now i cant do any of these. the reason for this is because : i gained some weight(lean bulking atm), i started to train legs(since end of march this year), got a job(in july but it was stressful trynna get a job and it is stressful doing the job lol). so for me rn, once i start cutting i feel like i can reach my past peak or so. the tip i can give u is try to find whats different from the trainings u used to do. or the lifestyle. maybe u switched up ur training routine, training schedule, reps and sets, intensity, not getting enough sleep, ur diet composition mightve changed, maybe ur a lil more stressed in life, etc. these things add up. also ur cns fatigue and peripheral fatigue plays a huge role in statics. so thts y one day, u feel so strong and hit prs after prs after prs but maybe the next time u train, u feel so weak and not connected so u lose ur motor unit recruitment and strength and the ability to push urself. ur brain cant send signals to ur body so thts y. tldr: try to find the reason