Wilf Sylvester use to use barbell squats, hacks, leg extensions and leg curls. When he won the short class Mr. Universe he used 400 reps of body weight only squats, leg extensions and leg curls. Not sure if it was one set of 400 reps or multiple sets to get to 400 reps. He was never clear explaining his routine. Made me experiment with body weight squats after my regular leg routine. I found they were incredible conditioning workout going full range down. I tried not to flop down with speed like cross fit guys trying to beat the clock but made every rep count. I think there is a lot of value in body weight squats.