Have we had this one yet:ever really,really socked anyone in the mouth?Do it right and you skin your knuckles.(I didn´t do that myself,mind you,but knew a guy who had skinned knuckles some saturday mornings..and after a while knew why..)
Now,in a film,no matter how often they punch somebody,or how hard,they never have.Also not if they,as aforementioned,but the fist through a door.They massage their hand but it´s smooth as a babys bum.