I dont use mine that much, but if i want to know about a stave,, then when I first cut it out or shape it and fresh wood is exposed,, I will get a pretty good reading,, usually at the handle,, if you are roughing it out and the moisture is high, you can bet it is higher deeper in the wood,,, so you know you better coat it again around the handle and fades or it will check,, as Badger suggested, when a stave comes in,, its a good time to check it,, to see where your at,,
I live in the high desert now,, and bow making is alot easier than when I lived in the high humidity of Texas and Tenn,,