IMO its all about flying in the night before and testing the walls to make sure the map is on point and then going to the hotel and rerendering your content library and making masks for zones
when this isnt an option I just whip out arena and map away... I rarely find myself with more than four layers running at one time before feeling like I am mixing up a batch of visual vomit...
generally at the real big shows you know your playing them well in advance and can get proper custom content together... but sometimes time f's you in the a and you just gotta stay up all night an map it out...
my only advice really is to play with the mapper as much as you can... also ae syphon is really awesome for making custom content during your overnight...
like Joris said tho... once you hit these rigs you generally have some pretty cool party tricks...