No need to let it sit uncovered overnight. That is useful for things on which you want to form a pellicle, or things that have skin you want to dry out so it gets crispy. Neither really applies to a butt. In fact, part of the reason that 78.9% of the posts on this site are about butts (completely unscientific guess on my part as to the actual percentage) is that there really are no hard and fast "rules" when it comes to making pulled pork from a pork butt. Aside from some of the more vocal members who insist on spewing their own opinions on the "right way" to smoke a pork butt, you'll find most folks just just season them and smoke them and don't worry too much about it. High heat, low heat, bark, no bark, wrap, no wrap, just let it happen. You'll have a harder time screwing it up than you think.
Basically all you need do worry about is applying smoke and heat for long enough to let the meat break down. That's it. All the talk about all the other stuff is just folks tweaking their own methods to their own taste.
Let's not forget, this whole method of cooking started off with a bunch of drunk guys throwing hunks of meat in a hole in the ground with a dying fire, passing out and coming back hours later to dig it up and eat it. Come to think of it, I guess it hasn't really changed that much. 😜