I lived in halls aged 18, and then again for a 15 month period when I was 24-25. Everyone in my university hals when I was 18 was also 18-19, and most of them were annoying and immature, but that was OK because I was the same age and it was just exciting to be out in the big wide world and mixing with so many other people. I made lots of friends, and ignored the ones I didn't get on with. That seemed to be the way of things.
When I was 24 I went back into education, and ended up living in a very unusual and remote hall of residence with other people aged from 18-30. Most of us were in the 23-26 age bracket though, and had already held down careers and in some cases mortgages, and had long term relationships on the go. Without exception, the most irritating people to be around were the 18 year olds. They had no boundaries when it came to personal space, noise, entitlement, and even cleanliness in the shared bathrooms. Due to the nature of the halls, it was not possible to live anywhere else at all for the duration of the course, but the matron took pity on some of the older female students and managed to get us housed in a separate area of the halls to the younger blokes, which was a bit of a saving grace really. She was fab, was our matron. Even if her dog did raid the laundry room and eat your knickers if you didn't supervise your washing!
I certainly would not voluntarily want to go back to living with teenagers away from home for the first time if I'd already seen a bit more of life.