I drink at least half a pot every day, with coconut milk, usually upon waking. But I can have coffee anytime and usually fall asleep just fine. I like it before I work out, definitely feels better that way.
It seems, in my N=1, that once I cross that threshold of casual drinker to daily drinker, additional coffee makes little difference to me. But if I am only drinking two or three cups a day and then have more late in the day, it does mess with me. Gray zone, there.
Gut health? Helps me poop. That's pretty useful.
Steak, eggs, potatoes - fruits, nuts, berries and forage. Coconut milk and potent herbs and spices. Tea instead of coffee now and teeny amounts of kelp daily. Let's see how this does! Not really had dairy much, and gut seems better for it.