when using one of the default programs, for example GMP what sort of numbers do you more experienced detectorists find yourselves digging, and is there a threshold below which you do not dig, where you know it is just rubbish

Main reason I ask is that I don't really get that much time out there and find I don't want to waste my limited time tweaking programs, as I know there are a lot of them out there

I am aware a lot of you like the tones and I think I would too but I can't get out enough to experiment yet