That’s it really. I somehow managed to get through 13 years of school education by going to the toilet during break times or asking to be excused during class if waiting for the next break really wasn’t on. There was no requirement to be able to prove to the janitorial staff that one’s being outside the classroom was officially allowed, especially when – as would usually be the case – one was obviously making the most direct beeline to the facilities.
It was clear to everybody that (a) you were supposed to return ASAP, (b) except in truly catastrophic circumstances, if one person was off to the toilet already you would wait for them to come back before asking to be allowed to go, and (c) it was mildly embarrassing to have to go during class at all (in German, the expression eine Sextanerblase haben – “to have a fifth-grader’s bladder” – means to have to go to the toilet very often; the Sexta, or fifth grade, used to be the first year of Gymnasium, or high school, so the Sextaner were the youngest, and by extension most immature, students around).
Generally, anyone wanting to play hooky wouldn’t turn up for class in the first place. Oh, and hall monitors aren’t a thing here, either.