I’m barely 5’-6-1/2 and currently weigh 230. In younger days, I weighed 211 and squatted 615. At that time the top 220’s in the ADFPA were squatting in the low-mid 800’s. Had I gone to 242, I would have squatted 700+ and been a bit more competitive. This sport favors the short/muscular/lean bodytype.
As far as failure goes, according to Coan and Karwoski (both coached by Gallagher), going to a slow grinding rep (RPE10) is the recovery equivalent of three extra reps. They also say that failing a rep can set you back a week or two, not to mention the confidence factor. They advocate a training style that stops each set at an RPE of 8 or 9. They also used CAT and when bar speed slowed too much the set was over. If you watch Coan’s training video where he did a 950 double, it looked like he could have done 4 reps. Yet he stopped at 2.
No one says that if you have an awesome day not to take some heavier weight, but its not a good idea to deviate from a program too often. If you do that, you have materially altered the program.