The reason I started this post is because getting into habits is not healthy and needs reviewing. At the moment:
1. In un-trashed ground where targets are few and far between, we (daughter and I) dig everything (after a solid foot scrape).
2. In lightly trashed ground, if the target double dips but it moves as we dig, then I
always give up. Maybe we lose some gold, but find more by not wasting time.
3. If it's trashy ground, we agree to leave all double dips without digging in search of that mellow sound.
I have read all comments with interest, but for the 4500, I'm now unlikely to change. Clearly this will be different for other machines.
I agree with some others' comments as we have found a few flat gold nugs (a coin may do it) that double dipped, but didn't move as we dug.
We've also dug some shocking signals (no double dips, but raspy and definitely not mellow) with my 4500 which rewarded. See the 1.72g "question mark" below (We name my larger/stranger finds for our log). You can see where it was folded as it was on the edge of a surfacing and was likely hit by machinery.