i doubt its the volume that matters most.
you could have the biggest volume anyone has achieved in one day by resting and lifting small weights with lots of reps
in the end you could easily get in over 100 sets of 20 reps.
IMO dont forget the basic thing(the stimuli). your brain must realize it needs to build more muscle. light weights will only make it build a little more, heavy weights it will need to build more.
in the end its the food that mostly matters.
and it varies on the individual.
i also had read an article that suggested rep ranges around 8-12, but it also said that bodybuilders get the “pump”(not sure if its the same as the pump that probably all of us have felt at some time in the gym) and only during that short period are their muscles as big as they can be, whereas without the pump they seem smaller.
on the other hand those who go for strength with higher weights build muscles and are tight 24/7. as tight as they are during rest they will be as tight and big during … whatever.
or something like that, i dont remmeber fully cause this stuff doesnt interest me all that much personally