I personally enjoy doing a set of 8. When I say I reach a new PR(bench or squat or DL) I usually just mean that I can finally do 8 reps of it. I could probably do pretty damn heavy weights if I did 1 rep max but I wonder: is it just a vanity thing like “look how much I can lift for 1 single rep” or is it actually something to help me increase my mass? Or would a 5 rep increase mass more?
Eh, the difference between a 1RM and your 8 rep sets is like 10 kilos at most. Maybe 15 on some lifts.
You can actually calculate it quite accurately: https://strengthlevel.com/one-rep-max-calculator
In my opinion 1RMs are only vanity reps. The workout you’ll get from them is from the extensive buildup and warmup you’ll have done to get that one.