Range Of Motion Questions

Hello All,

A question about range of motion. I like the idea of moving through the entire range of motion when training (squatting butt to the floor and all of that). Why would one not want to do the following exercises in the following way?

1.Dumbbell shoulder presses: Instead of stopping at the typical 90 degree at the shoulder and elbow point where the weight is even with the temple, descend all the way down so that the weight is at shoulder level and the upper arm is almost vertical against the body.

2.Dumbbell bench presses: Instead of stopping when the upper arms are paralell to the floor, let them descend even farther down so that the elbows are slightly below the bench.

3.Dumbbell bent over rows: Letting the back round out a bit on the descent (bringing the shoulder closer to the centerline of the chest) before starting the concentric movement.

Y’alls thought would be appreciated.

Jason

Why would one not want to do the following exercises in the following way?

I can tell you what I see in my gym in Ferrara, Italy. Complete absence of good trainers. After the 1st workout, beginners are left alone. They perform only isolation exercises very fast up and down with partial range of movement.
Noone performs deadlifts, a few performs Squats with a range of movement of 2 inches. What I see is many sets for biceps and bench presses (many trainers use the Smith Machine).