I never ever make a dig/no dig decision on what any screen TID gives me,if it gives a signal above 2 then it has to come out,if i was to rely solely on number then alot of decent coins/artefacts could well be left in the ground.Foil signals folks would normally ignore or any low numbers that in my mind would be a bad move as silver hammered coins would be left in the ground as just one example.Gold coinage or infact anything near the iron range is another signal that i will dig.....Audio is king and always will be,far more reliable that any TID,screens are only good in my mind for showing you the setting adjustments and not for TID.......of course its a personal thing and upto the individual.