Well, that's what I've been doing since I was 15, sitting through regular services. Since the time I was converted until now I felt that I was missing more in youth groups than what Christians normally did, so I never cared about it. I went to regular bible studies with grown adults, even when I switched churches several times since. The church I now attend actually has more young people than the ones I use to attend, but we do not believe in having separates studies/classes in this congregation. Most of the youth sat through regular services when they were children, and parents who attend from other towns nearby have their children sit through our regular services. I believe that is the healthiest way.
I've been to several youth groups in my (short) time, and they were worse than my expectations. I remember one from the biggest church in our town (500 members), and they were expositing the Shrek movie and how it teaches us Christian values. It came off as strange, especially how the youth pastor/teacher taught and the style of reaching young people. In all of the ones I've been to, to my memory, minimized Scripture and doctrine. As someone who knew basics as a young Christian, I was seen as an intellectual to others.