How Much Can One Bladder Bear?

I enjoyed the new Lord of the Rings movie, Return of the King, but it was simply too long. I think the first two did a great job of not trying to convey everything in the books and simply be great movies. The last one is as well, until the ending, or endings I should say, as there are several of them, each longer than the last. And it was here that the movie tried to provide a grand ending to the entire trilogy instead of just providing closure to the story. And it was here that I could no longer concentrate, the urine backing up into my brain – despite my awesomely timed-trip to the restroom during the very last preview – where my last thoughts were, ‘How long can one bladder hold out? Is there a statistical average? If so, has this been pointed out to Hollywood film editors?