Do you have any more info on his use of bodyweight squats? Did he do hundreds a day? I know he was wary of thickening his waist so he used the barbell squat with lower weights so this could be a reason.
First time I've heard of a pro bodybuilder using bodyweight squats, though I do know that many (pro) wrestlers do a lot of bodyweight squats as part of their training.
I have the article on Wilf Sylvester buried in my old magazine collection. He said he use to use squats, hacks, leg extensions and leg curls. For the Universe in 1975 he switched to body weigh squats, leg extensions and leg curls. He said he used 400 reps but he never said how many sets were used
Serge is listed in one of the "Three more Reps" series as using multiple sets of body weight squats.
I'm sure you don't want to hear about my experience but for awhile I was doing 50 ass to grass slow negative bodyweight squats after I trained legs with weights. The pump was unreal. I also feel they contributed to conditioning too. I know in cross fit they are big on the movement but like so many bodyweight stuff they do they cheat to get the reps in under the stop watch. They flop down on the negative as fast as they can and many times go shallow.
On the topic of using moderate weight for development Pellius wrote on this site there was a guy in his gym that did set after set of front squats with 135 and he had great thighs.
