I usually see sharks every trip. The offshore sites like Santa Monica Rock or the Chikuzen are best. Other sites we see them include the visibles, playgrounds, brown pants and Rhone. We have also seen sharks the last two times we dove angelfish reef. Most divers spend the bulk of the dive looking down. Try and train yourself to look out a bit more and you might see more. Most sharks get within visual range and turn and leave. If you were not looking out you never know they were there. Strangely the largest shark I have seen in the BVI was a big Tiger shark at the wreck of the fearless off Great harbor. Never saw another shark there but he got my attention that day!
If you want to see nurse sharks make sure you carry a dive light and look under all the bigger ledges.
G