I don't think many people in here are putting their chest to the floor. I try to go a bit lower than 90 degrees, so touching your [far hear] is that fore head?, to the stair sounds like a good range of movement. Let's go!
I touch my nose to the ground when I do them instead of my forehead. Simultaneously tapping my chest and little nasty on the ground as well. Then I try to fully extend my arms, but when I’m doing high repetition sets I may be guilty of not fully extending my arms. It is much easier after this long in the competition to control your form.