Another way I've taught the DA trigger press on a service auto is to think of the proper use of a canoe paddle or a boat oar: each is used in a long, smooth, constant speed STROKE from the moment you dip the blade of the paddle/oar until it finishes its stroke at the end.
From a student perspective, Wayne explained the concept to me this way, and it clicked in a very intuitive way. I've actually been thinking about "rowing" the trigger during dry fire.