A question of shooting technique when using rifles on moving targets.

In shotgunning the accepted technique is focus on the target, forget the gun.

In rifle and pistol shooting, using open sights, the accepted technique is to focus on the front sight and have the back sight and target off focus.

It is a biological fact that our eyes cannot focus on more than one distance at any one time.

So when shooting a moving target, ie wild boar silouettes, with a rifle and open sights, where does the eye focus? The target, the front sight, or is there some other technique?