Originally Posted by
Zorak
It's not "ok" in the grand scheme of things, but it's a concession to practicality. It'd be better to wear the mask the whole flight. If you minimize the time that it's off that's still better than not wearing one the whole flight. "There's a slight flaw so we should eliminate it entirely" is childish reasoning. Don't let perfect be the enemy of good.
The aircraft could hit turbulence when you get up to go to the lavatory, so seatbelts should be eliminated because you're not required to wear one when while walking to the lavatory!