When a new film comes out, how long it stays in theaters depends completely on box office sales. If tickets are selling, you’ve probably got a couple of months to catch it. If it bombs, you’ll be lucky to find it still playing after three weeks. And plenty of blockbusters end up staying, and staying, and staying—to the point that eventually you start to wonder who could possibly still be buying tickets. But how often does this sort of thing happen in the world of theater? On Broadway, sure, ticket sales determine the length of a run. But usually, no matter how successful or beloved a production might be, the run ends when it ends. After all, the real live actors have to move on with their lives, the theater needs to get ready for the next show, and come on, how popular can a play really be? Answering that last question with a “VERY, VERY popular” is the Annex Theater’s production of Peter Shaffer’s modern classic Equus—which has extended its run through this weekend due to popular demand.