Boarding school
Wearing shower caps in the nightly enforced shower. We were allowed 1 bath a week on a rota, and even then as a 12 year old Matron had to run it for us 'because of the hot water'. She would give you 50cm water. The senior boarding house (3rd form onwards) didn't even have baths.
We were never allowed to watch the TV. Ever. The only time we got to watch it was if it was someone's birthday and they had a film.
Netball skirts and PE knickers. Nuff said there. Except one of the masters would make you lift your skirt to check you were not wearing your own pants or cycling shorts. That particular master is now serving a long sentence for offences against young children.
Showers. Communal ones. The mistress checking you had showered. The period book she also held. You were allowed 1 week off showering every month. Anything more than that required a chit from matron.
Town leave on the weekends. We had to go in groups of no less than 4, had to walk a particular route (I.e. not the shortcut) and were allowed £2 a time 'incase we visited McDonalds'. By 3rd year I was wise to it and in my monthly book my Mum used to send me, she would also stick a few tenners. Money in letters would be intercepted. Money in books wasn't.
Letter writing. Each Sunday after church (yep, my school had a church on site). In the junior boarding house the duty mistress checked your letters to make sure you were writing 'a proper letter'. A letter writing set was mandatory.
Shiny shoes. Your shoes had to be polished at all times. Any kind of remotely decent shoe banned- it was strictly DM's. Those things take years to wear in and be comfortable. If your shoes were unacceptable you would get a chit and a detention. 6 detentions in a half term and you would get a head's detention. I managed to achieve this in a day and a half once.
I didn't go to Mallory Towers, The Chalet school or even anything like it. This was in the mid 90's. Unsurprisingly I got expelled when I was 16. I think the school had finally had enough of me.