I left at 18, but did move back for several month sround 30 when I came back afer working abroad and was on the dole...
Alright for a month, but after that things start to grate a bit. Particularly with the old man, partly cos I was just getting up when he nipped back during the day for his dinner (self-employed tradesman). But tbh I think there something about 2 grown up blokes in the same household will always end up circling around each other if they aren't to get on each others tits. My mum was no problem.
I dunno it depends on circumstance, I always thought it was a bit sad past your early twenties, but seems fairly normal nowadays, sometimes it's the best arrangement all around if you can live okay with each other.