Just watched one change the timing belt in my car.Bolts, screws that I wouldn't have shifted in a million years came loose with no apparent effort.The right wrench was picked up each time,first time, everything was done methodically, in the right sequence, confidently, knowing how much force could be applied to a recalcitrant item without breaking anything.There were no misplaced bolts or screws, everything was reassembled without a hitch.All this and a gom like me looking on and holding a conversation.Considering what I pay doctor bob for 10 minutes to look down my throat, or other 'professionals', mechanics I consider vastly underpaid.