This all depends on the program, what barbel volume is desired, and how everything is intended to fit together.
Generally, the higher volume programs are done in 5’s PRO (5’s across sets and weeks).
Then, when the barbell volume drops, you go for PR’s. This is when the traditional 5/3/1 rep scheme comes bank into play.
It helps to always remember that 5/3/1 is at it’s core, about certain principals, and not just a rep scheme.
Hope this helps!