FFS. It's not rocket science. Rule Number One in Effective Education:

[proud2BlibKansan]

4. You're missing an important point

TEACHERS don't create policies that say kids can only go to the restroom at certain times. ADMINISTRATORS do that. And teachers, if they want to keep their jobs, are forced to respect those policies. So even if they want to just let a child use the restroom, they can't.

Every building I've worked in with a restricted restroom policy also kept those restrooms locked during class time. So no, I couldn't just send kids when they asked.

When they insisted it was an emergency I sent them to the nurse.

DH is a maintenance employee at a high school. He spends well over 50% of his day cleaning up graffiti, mainly in the restrooms. And every bit of that graffiti was put there by kids who were UNSUPERVISED. The school is unable to paint classrooms and other areas in the building because the entire budget for paint is being used in the restrooms.

So the real lesson here to teachers is SUPERVISE YOUR STUDENTS.