I usually dig it all. I don't know how many times I have walked away from an iffy signal, then after walking a few feet, I come back to it and dig something nice. I've learned to dig ALL iffy signals in supossedly hunted out sites. (and another secret... hunt close to the road or parking... most people walk away from the car before beginning to hunt. I found a nice sword hanger about 2' past an old barbwire fence that everyone had to cross to get into a site. I know that most hunters were walking past the fence and into the woods before beginning to hunt.)
If I am at a place, like an old, (but not too old), homesite and I am digging lots of zinc pennies I will start leaving them. If it's an older homesite i'll dig them because some of them might be IHs. You can't always dismiss things because they aren't deep. Especially if there is a grade to the ground. I've found eagle buttons, coat and cuff, on top of the ground at some places where the ground is hard and there is a slope. I found a roundball a couple of miles north of Kennesaw mtn. It was sticking out of the ground... on a flat lot. I eyeballed it. No slope at all there... just flat ground but it had been graded at some point. Who knows what was done to the ground 50 years ago?
I always dig and keep bronze pennies, clad, and everything else. The trash goes in a bucket and I sort it from time to time. If a zinc penny is too badly corroded I will trash it. I dig iron too, you never know what it might be. I've dug some nice iron relics and you might unmask something really nice.
Then again... i'm glad most people decide to not dig those pennies and iffy targets, it leaves them for ME!!!
OH... another story, again just off Barrett Pkwy they were building a church, Keeensaw Mtn less than a mile to the south. I found out about the site after the local club had hunted it hard along with everyone else in the area.. but I went anyway. Most relics were found near the north end of the site. So, after it was "hunted out" I dug, in the same part of the site a zinc time fuse holder, w/no flange from a 20# parrott shell.. it was about 2" deep. I guess everyone thought it was trash.. it's all I can figure. I saw one yesterday at the Relic Show in Marietta but in worse shape than mine, they wanted 60 bucks for it.
I don't remember what detector I was using but I checked it with my E-TRAC and it read 01-40 just like a silver dollar. I need to get a bunch of stuff out and check it with the V3 and make a list.
Nevermind... don't dig stuff unless it gives you a perfect signal and you are sure it is a good target.
J