That's an excellent observation if you're using new wood from the big box stores. There used to be sellers of specialty treated lumber that was dried to 15% after treatment but even then 15% is a bit wet if the project is out of the weather.Only problem is most of it is 99% moisture content. Basically, waterlogged. To get it dry enough to make anything out of takes a long time. I woudl sticker it for 3 or 4 months before I thought about working it.