I saw it in NYC at least 40 times, and I'm far from a stalker. I think. I hope. Cheap seats, lotto, hanging out with friends and people from out of town. It was kind of fun. I've never done that for a B'way show and never will again, but it was great while it happened. What Plaid Ducky said about seeing different cast do different roles, seeing Melissa Etheridge, Danny Havok, Billie Joe, and almost every St. Jimmy understudy do the role and various other people filling in for the main cast. It was neat to see everyone's take on the roles.
People do this all the time with Broadway shows. I don't, but some do.