Yep, apparently you can overdo it with these things. When you first turn it on, it's in "on" mode - no regulation. But you can set the thing to maintain whatever R.H. you want. My goal is to keep the shop RH at least close to that in the house. I think I'm going to keep it around 50-55%. I don't know, I'll have to see how it works. I'll be happy if it just keeps the humidity more STABLE in the shop.
Those dovetails corners I made last week - I brought them upstairs and left them. They started out snug (mallet needed for assembly), but now they are noticeably easier to pull apart. No visible gaps, but still kind of indicative of a problem, IMHO.