I have two DDs who are 7.5 and 10. My DH and I take turn about doing their beds every night, which involves us getting into bed with them to read them some of a book and then giving them a cuddle before they either read themselves for a bit or listen to an audiobook.
I've become aware through friends that a lot of children who are the same age as DD1 just go up to bed themselves and read/watch tv etc.
I'm 100% happy with our current set up and will continue as long as our DDs want us to but I'm just interested in when your DC went to bed independently?
I honestly can't remember at what point I just said goodnight to my parents and went off to bed myself, but it was definitely before secondary school. I've got very fond memories of my mum reading to me though.