i think it depends upon what you're doing.
For powerlifting squats - the weight needs to be on the heels as the appropriate power position and maximum strength for most is achieved when the shins are as close to perpendicular as possible.
For squat cleans, snatches, etc. - throughout the movement, the weight position on the feet changes. But when you're drivin out the hole, at least I return to driving from the heels, but not as much as do when doing the types of squats listed above.
Personally, my thought is that with OHS and front squats the weight on the foot is more centered. Both on the ball and the heel - balanced. At least it is for me.
What I'm having a hard time getting though my thick skull is how the weight should be distrubed on the foot when you pull.
When I deadlift, I pull from the heels. I drive my feet through the floor, from the heel.
But when I clean or snatch pull, I start that initial drive from the heel, then try to balance it out when I go into the scoop or power position. It seems to me that the balance would need to be on both the aspects of the foot when you're getting ready to jump. you don't jump efficiently from your toes and you don't jump efficiently from your heels - there needs to be balance.
Am i remotely close on this. I got now clue. I am but a padawan.
All the best,