All the time.
I play in an educational trust group that has loads of ensembles. In the jazz ensemble there are kids, some as young as 14 with anywhere from Grade 3 to Grade 8.
I am definitely the hack in the room. My only saving grace is that after 30 years of playing I can improv to just about everything - I'm working on my reading skills but I'm only about Grade 2 or 3 at a push for sight reading.