I'd like to think I clamp on the grip and it just does it's thing but I am aware that on some shots my grip is not as tight as on others. Just like on some shots my trigger pull is different. Or my sight picture is more or less refined. If I had to do one shot from 50 yards I would grip hard enough to ensure the sights remained on target through the trigger pull and the shot breaks. If I had to shoot 3 targets while moving 5 shots each, my grip would be much tighter. Just like the 5 yards shots my trigger finger would slapping and lose...whereas at 50 yards it would not. I want my grip to do two things. 1: Keep the gun properly aimed as a I pulled the trigger. Essentially so I do not pull the gun off target during the pull and 2: return the gun as quickly to the spot I want to take my next shot.
My suggestion is whatever you want the gun to do, grip hard enough to make it do that.