Ideally the student should start as ‘high’ and as far back as possible and be able to snap the bar no further than about halfway down. In this scenario the trail arm should stay bent and you should still be in posture. You won’t be able to float the foot, however, you should feel max ground pressure in the lead foot when you torque the bar.
The mistakes people make:
not far enough back
quickly straightening the trail arm
not torquing the bar (not enough power)
letting the bar come down to far (almost to impact)
I do have a drill to float the foot, you start with both hands ‘down’ and then load lead foot then explode off of that foot and pull the bar and pop it.
I hope it helps!