I mean, a jack in the box always pops out at the same point in the song right? And yet it's still surprising. But you're not pressing a button to make it activate, it happens at a point abstracted away from your direct attention. It's always worse beforehand if you slow down and try to predict when it'll happen, so you just keep going without regard for the exact moment it pops. When it pops, if you react, that reaction follows the pop instead of preceding it.

The point is that you train your body to continue with a smooth continuous motion until it lets go on its own, and you train mentally to focus on the draw instead of the release. You aren't in a position where you're anticipating opening your hand and tensing up your body to get ready for the shock.