S.W.
Once a day?!? Are you kidding?? I would have been protesting that from day one!
The school my daughter attends has bathrooms that are easily accessible from every classroom and they don't even have to ask permission to go there! She's in elementary school.
Wow, kids (people) need to go when they need to go. Is this an elementary school? Aren't they having "accidents" with this ridiculous policy? What if a kid has a bladder infection or other medical issue...or just had an extra glass of orange juice for breakfast?
I think I would take this right to the principal, or top administrator at the school. I would describe in detail what they are going to start seeing (blood stains on pants and skirts) if they don't let girls (all students) use the bathroom as needed, and without any embarrassing requests needing to be made to do it.