What I am saying is that most of the places I hunt have pretty consistent mineralization. I hunt the same type soil most of the time and it seldom varies by more than a few numbers within the site. I don't hunt beaches one day, the city park the next and prospect on weekends. Most of my hunting is done in what is now farmland.
My recommendation from that "long ago" post still stands. Until you get use to what your detector is telling you, lower the sensitivity before you attempt to set the Ground Balance. Once you set the GB, raise your sensitivity up to where it becomes "unstable". Then back it off so it don't drive you nuts. After you have some hours on your X-Terra and are familiar with how each setting affects the operation of the detector, you may find you don't need to lower the Sensitivity prior to setting the GB.
For those using the Auto GB on the X-70 model, you may not have to change your Sensitivity once you find a setting that works well for you.
I view ground balancing a detector to be nothing more than discriminating out the mineralization. If you don't tune the detector to "ignore" the mineralization of each site (GrdBal), you risk a reduction in the depth of detection, poor target separation, low sensitivity to small targets, excessive false signals, missed targets etc.
HH Randy