Sometimes a shoot does not get as much time as it should. Could be for a variety of reasons, including muses taking it easy and not sticking to timelines, or finding the location challenges and all that. But the idea is obbviusly to quickly put it all behind you once you start shooting , and to make the best of everything that is available at that moment. I always say, never cry over spilt milk, just save time by ordering the cold coffee.
Cheers
ash