took me about 4 hours to skin the door, por 15 my steering linkage, epoxy prime the door shell, eat a jimmy johns #9, and take all of the pictures. And that was on a Sunday
If your just skinning a door I would say for a first timer it would take about 3.5 hours. You have to think about taking the door off the truck, R&I Door handle, lock cylinder, window, vent window, belt mldg, window weatherstrip. Remember this is not a race. An average modern door pays about 6.5 hours to skin but that includes all of the door tear down and removing the door from a car.