Angelina It's not a fixed interval at all. I've tried asking for the key only for them to not give it to me. Recently (I mean from last year) they give me the keys every few months to have some time. I've mentioned before, it's not a lot of time, but enough to have some alone time. So you could say they surprise me.
At the start it was to make sure I cleaned up well, for my mum the cleaning was a big deal (and rightly so). But once I started wearing it 24/7 from 18 yrs (ie after school) they were more strict about the cleaning, making sure it fits well and all.
I suppose I behaved well and cleaned myself pretty good so my mum just let me know that they don't need to be supervised one day. Not sure if something else was also at play here.
I feel under 18 is illegal everywhere? 16,17,18 those kind of ages? Or am I mistaken? Anyways most students don't indulge in any. But you might not know about a huge coaching "industry" here in India where they prepare kids for exams (it's horrendus if you look at the stories online) thier the students sometimes indulge in smoking, alc, and sometimes intercourse. It's done as a form of stress relief. I know someone who gone through that. It's really mentally taxing for them, you should maybe check it out if you get time.