Same here with the gray. It really depends on how long I'm staying at that spot. If I'm just there for a few nights, then I leave it shut out of laziness.
And somebody else mentioned shutting off the fresh water valve at the spigot when leaving for the day. I do that too if we're going to be gone for a long time. It feels superstitious, especially since I never do that with the pump when we're boondocking.
So many of our rituals feel like the actions of superstitious natives, especially throwing chemical tabs down the toilet like virgins into a volcano. I quit that one years ago.