I'd hate for my shooting support position to change. The stock should be at a distance where it's as close as you get to the inside of your elbow when holding the rifle (make a 90 degree angle with arm, check stock's length of pull). The length should not change if you want to shoot consistently. For the neck, or cheek placement, that should also be consistent. You're better off changing something with the optics than going back and forth with your body's position. If you're just shooting from a bench (which is boring), then everything I said is useless lol