the boys at Whitgift are most certainly not accompanied to the toilet. Neither are they accompanied off the site when leaving to go home, or escorted to detentions etc.
They are accompanied off site. As are the boys at Trinity - staff wait at the bus stops with them and supervise/ensure they get on in an orderly fashion - and will make them get off again if they are rude to anybody such as the driver or passengers. Staff are on bus stop duty until at least 4pm, if not later, to allow for detentions, clubs and generally hanging around or waiting for a particular person to come out.
The escorting students to and from the toilet reduces the times where they hide in there on their phones, meet up for vaping or smoking, dealing, collecting weapons hid earlier in the day, finding other places on site to hide, meet boyfriends, have a laugh and a joke, vandalise said toilets, self harm or become genuinely and seriously ill and nobody knows where they are. And the prospect of being escorted at every lesson means that the usual ones who do anything rather than sit down and get on with their work think twice about it by the third lesson when they've already had two trips.
I've worked at a place that introduced it - apart from drugs, knives and cigarettes/vapes, alcohol and stolen goods were found at different times hidden in cisterns, behind cistern boxes and in the ceiling. As were items for serious SH and phones - the latter could be extra ones related to gang or CSE grooming.
It's also been possible to pick up on girls with period issues, as having to escort the same girl five times in the day means that you can have a nice chat about how it isn't something she has to put up with, she can see the GP about it, that a girl going there because she needs to throw up could be pregnant or bulimic or severely anxious, etc, etc. Or the kid who was a bit twitchy when going in is quite possibly under the influence when emerging, which gives grounds for not just seeking medical attention for them, but searches - as too many will have parents who will say 'oh, they were tired and you were picking on them' when they have pupils the size of the moon or smaller than a pin prick/are bouncing off the walls upon emerging.
It's a blunt tool, but an effective one for safeguarding.