This is true to a certain extent. I can hit what Im aiming at like that but to get truly good groups at range with a pistol you have to focus on the front sight. Of course under stress you target fixate anyway and cant focus on the front sight. Thats why I went to an RMR.
Do your CCW with an RMR? And yes, if i am shooting at a paper target or do something more precise with my pistol i still close my left eye and probably have my tongue out trying to concentrate. It is then drill when shooting fast or from a holster or shooting steel is when i try to shoot with both eyes open and focus on target.