> often spend many hours per day for most of their career Assuming you mean running smoke machines, no they don't. Smoke machines are occasionally used, but no

> often spend many hours per day for most of their career Assuming you mean running smoke machines, no they don't. Smoke machines are occasionally used, but not in most plays, let alone for hours. And even if the were, most actors rehearse for weeks or months between plays, and nobody is using a smoke machine on rehearsals, except maybe in the last few.