Some time ago PPC shooters had the same concerns. Seems that a lot of the competitors were looking/glancing at the ragged hole in the target rather than the front sight. Takes a brief moment for the eyes to shift gears and change focus back and forth.
A quick fix was to change the sights to where the correct sight alignment was centered on the neck of the target, but the groups were printing in the 'X' well below the line of sight.
I'm told that today's crop of super competitors don't need POI lower than POA to maintain concentration.