Wetting your mud is a trap, I don't care what Chuck says. I tried it once on a small patch job and ended up with a soupy mess that took twice as long to dry and sagged right off the ceiling. If your compound is mixed right and you're not rushing, you don't need extra water to make it "flow better" - that's just masking bad technique. An old timer told me the same thing and when I pushed back he admitted he only did it on hot, dry days in Arizona, not for regular work.

Does anyone actually consider the environmental cost of tossing old shutters?

Oh man, I've seen that exact thing happen way too many times. The problem is people assume old trees are strong trees, but decay can hide for years inside a healthy-looking trunk. I've had two big maples come down in my yard just because they looked fine from the outside but were hollow inside from old wounds. You really need a certified arborist to check for things like cracks near the base or mushrooms growing on the trunk, those are dead giveaways. Mulching around the base too deep can also cause rot near the soil line, so keep the root flare exposed. For that oak on Elm Street, sounds like the limb failure was from included bark in a tight crotch, which is super weak in wind.