I can poor water from a bottle of water onto the poo on my arm and I'd still think it'd be unclean. I'd need some positive pressure to think otherwise. Oh, and some soap.
https://media-cdn.tripadvisor.com/media/photo-s/06/b7/48/74/...
Some of them also have variable temperature.
On our bicycle-journey through Asia we had a dedicated squeezable poo-bottle and poo-soap ("Kackflasche" and "Kackseife" in German).
Was disappointed.
You know a high pressure hose that pushes back when you spray it? It was like that. Vicious.
In terms of duration, it was just like a normal tap, I assume fed by the local water supply so you're not limited.
I'd use it for max 10 seconds to feel fresh.