In the Mil we often worked until we dropped, but then our squadron crews did the same. Later, Vulcan aircrews flew all the way to Port Stanley and back without whinging about crew-duty hours. Their engineers worked through many 'ghosters' preparing the aircraft and improvising lots of local mods along the-way. So, its quite possible that long hours at the wheel aren't as exhausting as they are made out to be. Personally, I reckon disturbed diurnal rythms are the real crippler.