Gawd - what a bunch of crap!
I don't know how often anyone should pee. But I do know the answers in this thread are mostly piss.
Here's the common sense "deal." Off hand, you should pee about as often while riding a bike as you do when you are off a bike. But, I wouldn't be surprised to go a little longer without peeing if you are riding a little harder, and interested in getting where you are going.
Much of how much you need to "pee" is determined by genetics, but in any case I doubt going nine hours is a good idea. My own "max time" seems to be around six hours.......