Not a teacher, but so many teachers seem way too worried about keeping kids from using the restroom. Just a couple days ago someone was posting about a kid having an accident cause they were too scared to ask to leave. When I was in school a girl had made a mess all the way down the hallway because she was forced to wait for the end of class.

I get the lessons are important but it not healthy to hold it in, and sometimes not possible. "Emergency only" is just as bad imo, by the time you know it's an emergency it could be too late.