Well, it is all about stimulation in the end.
Squats and dead lifts boost testosterone levels, GH levels and stimulate the CNS.
This is good, and if the range is good, it works the whole body, even the core.
It is a natural exercise and to be honest the biggest legs I ever saw were guys that had a nice squat, not leg press, not extensions, but the squat.
Rep ranges will dictate hypertrophy depending on the person but the higher rep ranges tend to be more effective, with the exception of those guys that can fire all fibers when going heavy, but that isnt for the normal dude in the gym.
20 rep squats are killer, even work the diaphram, and will wind you no matter what.
Sprinters do squats, football players do squats, why?
Because it is the power out of the hole that matters in their sport.
Now granted this is bodybuilding but once the mass is there then the isolation exercises work well for seperation and isolation of lagging body parts.
Never seen a big squater with small legs.
Never seen a big dead lifter with a small back nor small traps.
Bro, if you focus on the lifts that matter and blow off the crap that doesnt, focusing on that that matters, better gains will ensue.
You can get condition too with stuff like clean and jerks, running stairs, etc.
HIIT, HIT, will get you into condition and you wont have to worry about the other fluff stuff.
Id like to comment more later on some stuff....lol....stuff....lol