The way our classes are structured, the beginners class flows seamlessly into the mixed level class. As such, our BB starts with one core concept and carries it through to the end of the mixed level class.
Like many others, I stay through the whole thing. However, when we roll later, I rarely use the advanced moves. I may have drilled them correctly, but they are over my head to execute. I concentrate on the core concept that was drilled with each new move, and maybe one or two of the techniques related to it.
Maybe when I'm a bit better I can follow Calibur's advice.