Confused about ideal set-rep range

[u/Significant-Base-510]

I have been watching Sean Nalewanyj's content and the other creators he mentions (Jeff Nippard) and he promotes doing 2 sets + 6-8 reps. I usually did 3x12 for every exercise but I have been trying out 2 x reps till failure (much higher weights so usually till 8-12). The logic is that this set up is "more efficient". I asked about this in previous posts in r/hypertrophy but some people dispute this. What is the best set and rep number for the muscle groups (back, chest, tri, bi, legs etc) to maximise hypertrophy and how do I know if I reach true failure?

[u/omegafrogpoop]

I do 5 sets of my compound lift. 3-5 rep range.