Yes, wooden spring.
After I hit full draw, I make adjustments when I draw it in the hand.
I'll either have my wife or daughter take a picture, draw in front of a mirror or in front of a window at night.
I pull from the center on my rope and pulley so this compensates for it.
Actually, nothing compares with how you hold the bow.
I imagine digi tillering takes the place of having other bowyers look at your tiller.
My daughter has a pretty good eye for a tiller but this way I can get it looking the way I want while drawing. Jawge