Personally, I leave my plug in. Granted, I do about as much waterfowling as pheasant hunting, so it's as much out of convenience as anything else. Some guys will take it out for pheasant hunting, but I rarely even use the third shot, and for me, shots 4 and 5 would be a waste of ammo anyway.
My personal choice would be that after shooting three times, I need to shift my focus to picking up the bird(s) that is/are down. It's amazing how much ground a wounded pheasant can cover in a short amount of time. I would rather stop shooting and make sure I collect 100% of the birds shot, than continue shooting and increase my chances of losing a cripple.