Except for some ones (made out of that "foil") we had for a school event, some of which got loose and floated to the ceiling - another member of stage crew was insistent that "they'll be down by Monday".
They weren't... Four months later, I actually had to shoot them down with an air-rifle.
That brings back memories. We have a high ceiling in one part of our house and a helium foil balloon got stuck up there. After a while I shot it with a BB gun. There is still a BB-sized hole in the ceiling there.