Your eye should not move once you have a solid anchor, just as your sight pin does not move around inside your peep sight once you have a solid anchor. After you have used the No-Peep for a while you will find you do not need to look at it because now you come to a consistent anchor point when you draw your bow. The No-Peep images will be aligned and you can see them in your peripheral vision if they are not. It works as a tool to confirm you are doing everything right. Most people who start using the NO-PEEP find they have several problems in their form that keeps them from shooting to their potential.
Some target shooters use the No-Peep with a peep sight to improve their form.
Archers shooting Olympic type archery use the No-Peep to develop their form. Gripping your bow too tight or tension in your bow hand or arm causes the bow to rotate in your hand. Bow torque causes your groups to string out left and right. When the bow rotates that line moves and the images no longer align. That tells you that you are torqueing your bow.