Motivation constant when spinning disk?

I was at a gym defended by two pokemon, including one of my own. I stayed there for about two hours and kept spinning the photo disk about as often as possible. During that time, the motivation of both pokemon stayed constant; it did NOT decrease...except eventually by 1 after I forgot to spin the photo disk for a few minutes after I could have.

Do pokemon defending gyms maintain their motivation if there is a trainer from their team spinning their gym's disk?