I’m of the opinion you shouldn’t squat all the way down. If you do squats after speed work I wouldn’t want to stretch the hamstrings that much. JThighs parallel to the floor is fine.
I have recently switched to a college program from a (very good) high school one, and one of the biggest differences is that we must squat all the way to the ground.
it has not affected my knees at all- that is a danger only if your knees are going out over your toes, in which case you would be squatting improperly by leaning forward and using your back (and putting pressure on the knee)
-we do full squats every time- front and back alike
-we have been doing equal reps to what you might expect for normal parallel squats- in fact a lot more than I was used to doing. I never actually tested my max squat going parallel, but based on what I used to do for 4x6, I did about 65% of the same weight for sets (front squat to ground) of 6x 6-8. not exactly a direct comparison… but basically I had to take it down a decent amount.
I feel that going to the ground really works my whole quad up to the top, I was reluctant to switch over but now I like them.
I squatted ass to grass for a while, with heavy weight and never had a knee problem…I think a difficulty some people have with full squatting is the fact that they have to use less weight and the fact that it does actually take a decent amount of active flexability to perform one…and yes it was a quad/glute dominant move, mine blew up from them…