Not even. It's more about the speed, and you can 'angle' it. There is a small sweetspot that I'd say ranges about a...45 degree arc from the center. The best way to practice shield-dropping I think is to practice simply crouching on platforms as fast as you can. It's almost identical to the speed and precision of a shield-drop. It may actually be the same timing. I have no AR to tell. But it definitely helped me.
Just crouch, stand, crouch ad naseum. You'll get the timing very fast.
Try angling it down right and down left a bit. Within a 45 degree arc from the center. Pretend the angle faces down like an equilateral-triangle.
I made a crappy diagram:
Past the blue is too far. Yellow is the wrong area to be pressing toward. Red is the area you should be aiming for. Try to stop abruptly at the blue line if you can. If you can get the knack of it.