The set-building stage of the production has several stupidities that I keep seeing over and over again.
Crew misusing toxic chemicals around unsuspecting crew members: I once was sprayed in the face with stay-put. Now I'll probably grow horns. Oh wait, looks like I already am;)
Electrical and air cords all over the place: Once I saw a 12 step ladder get tangled up in a cable and it fell over, hitting a crew member in the head.
Crew ignoring painters tape across a set entrance: The floor's wet; they just painted it.
One of the saddest stupidities I keep seeing, however, is that one of being stupidly stubborn. Like the ratings system that is stubbornly resisting change, like the pot prohibition that is stubbornly preventing a viable economy: A design decision that is resisting a necesary revision because of, dare I say it, ego?
A Designer that refuses to alter a design to accomodate shootoff issues, will most certainly cost the production an extra cost either in stand-by renovations or in post. A good Set Designer will be able to illustrate a shootoff issue on paper well before construction begins. If in doubt, ask the Set Designer for a camera section. Stupid extra production costs hurt.
It happens all the time.