I mean those commercial toilets are what you'll find in a lot of office environments, schools, stores, etc etc. And it's the time when you're likely present in

I mean those commercial toilets are what you'll find in a lot of office environments, schools, stores, etc etc. And it's the time when you're likely present in a room for someone else's flush. And, you also have no idea of who's using it. In a household, one will probably have an okay sense if someone else is sick (eg flu).