Some people have a need for irrigation, particularly if they have difficulty emptying. But, it is not a general recommendation for all pouches as far as I know.
That said, it is true that the small intestine is not intended as a reservoir for stool. This is why you do not want to slow the gut too much. But, over time, the ileal pouch mucosa evolves on a cellular level to resemble colonic tissue. So, it adapts.
Having stool come out as fast as possible sounds like an intolerable existence!
Jan