I thought it was already well understood/researched that it's not the weights that matter, but effectively taking your sets to muscular failure. While one might think "I can do 50 reps with low weights" there is practical aspects to this - you don't wand to spend hours at the gym, and doing heavy weights at 5-7 reps is sufficient as long as you are close or at muscular failure.
There are a few issues with taking every set to failure, the most important being that it will substantially increase your risk of injury. It sounds great until you consider compounds like the deadlift that can ruin your back if your form is bad, and by definition, going to failure means your form will be imperfect at some point. There are lots of macho powerlifters out there with permanently ruined spines who will p…
As I understand it taking a set near failure works reasonably anywhere between 5 to 30 reps, but 30 well controlled reps with good form * 3+ sets for each muscle group gets really boring.