Avatar was awesome indeed!

next design, prosthetics take a long time to put on
you've seen xmen? for mystique and nightcrawler they would spend a good 8 hours a day just sticking that stuff on.
after 8 hours of staying still the actor isn't really going to be at their best unless they put the prosthetics on while they sleep?
and that's 8 hours a day that could be better spent planning/filming/dubbing
not only that but you need physical resources like the body paint they use that has to be sprayed on each time, and then also sprayed on again when it starts to come off during shooting
it's kind of a waste of physicall reasources imo