if you are roughing out a stave you have access to wood under the surface,, sometimes cutting off a belly cut etc, you can get a good idea what the wood is going inside, when I lived in Tenn and Texas, moisture content was difficult to manage, the moisture meter helped, I live in New Mexico now,, I hardly ever use the meter,, unless I am curious about that state a new stave is in,, I am not advocating using one,, many bows for 1000,s of years made with out one,,,, i found it useful in the humid climates,,