After you Auto GB the X-Terra, manually adjust the X-Terra a number or two toward zero. Doing that might make your X-Terra "chatter" more than it would if you had hunted in the Auto GB setting. Some folks don't mind putting up with a little chatter and others don't like it. Myself, I don't mind hearing it. Occassional chatter at the end of a sweep pattern lets me know that I am running "hot". If the chatter noise is low tone, I go on as I have learned to ignore low tones for the type of hunting I do. If it makes false signals in a high tone, I sweep back over the area to see if the audio tone is consistent. If it is, I dig it. If it isn't, I go on. If it makes false signals on every sweep, I am either getting tired and lifting the coil off of the ground when I change directions. Or, I have the darn thing set too positive! If that is the case, I can set the GB back up a couple numbers or reduce my sensitivity. (I seldom lower my sensitivity.)
Like I have said before.... don't get caught up in the numbers. Set your detector for what works best for you and enjoy the hunt! JMHO HH Randy