Billy strives to be a complete musician. Rather than always trying to advance his own career, he has been involved in group projects and has worked as a sideman with great success. As examples, he was a member of the Mingus Dynasty, he co-founded percussion ensemble Coloquim III, and he played with The Great Friends and Quest.
Hart has recorded 8 successful albums and appears on literally hundreds of recordings as a sideman. The fact that so many great musicians want Hart as their drummer is testament to his great playing. Hart is still highly energetic and in demand as a musician and teacher to this day.