Under "normal" circumstances I can usually go about 2 hours between pit stops. But sometimes, not sure whether it's elevation or low humidity or what, I have to go CONSTANTLY, like every 30 minutes. At El Tour de Tucson last year, I stopped at every single rest stop the last 40 miles because I HAD to go. It was not psychological, it was not my bike fit. I had the same problem in Yellowstone this year, and was always ducking into the bushes. Maybe I do over-hydrate (usually 1 bottle an hour), but I still think excessive nature breaks beat dehydration.