... it would seem your overlooking some opportunities.
You have been detecting for awhile, it seems, being a member here since 2005. There is probably little we can recommend that you haven't already heard. In that time, you have surely seen that tot lots offer things in the lower conductivity ranges worth finding. Almost daily, there is some silver or gold trinket found in these places by our fellow coil chasers. A lot? Maybe more than you think, when taken as a whole.
It depends on how you look at it.
I know people who spend hundreds, even thousands of dollars to go after gold nuggets. They normally live under often primitive conditions with bugs and snakes their constant companions. They move tons of dirt and rock, wallow in creeks and washes and climb treacherous hillsides in search of a few flakes of the yellow metal. Sometimes they succeed - more often the get skunked. In the end, they consider themselves having done well if they can recoup some of the expense with a few gleanings.
Contrast that with the average tot lot hunter. He works in clean wood chips, sand or grass. He rarely travels far from home and is usually within sight of a burger stand. The only bugs he sees are an occasional ant or mosquito. If he is diligent and knows his craft, it is rare for him to be skunked completely. Often enough he gets the gold he seeks, in the form of gold jewelry. Some who specialize in seeking jewelry find more than just a little of it, too. They can count yearly totals of gold and silver that put many more traditional gold prospectors to shame. Often it is just a lot of little items summed into an aggregate total. Sometimes, the annual tally includes some rather big pieces. It is always different.
I know the lowly zincer seems not to be worth the trouble to recover it. It is far more tempting to run the discrimination control up and "cherry pick," recovering only the paying coins - quarters and dimes.
But it is among the zinc cents, screwcaps, pulltabs and foil balls that you will find the most precious metal that we seek. I have found class rings, engagement rings and two sets of gold bridge teeth in tot lots, items that would have been missed with the DISC turned up to cherry picking levels.
And yes, I also found a lot of nonferrous trash in the bargain. Like any other treasure seeker/prospector, I take the bad with the good.
It is up to you to do as you wish and not for us to tell you what that must be. But after 20 years detecting, I'm certain of one thing:
Every detectorist has dreamt of hitting it big - at least once - with a nice piece of gold jewelry. They certainly wouldn't throw it back down were they to recover it.
Either way, that cannot happen if you have it discriminated out at zinc cent levels and below.
Got out today and snagged $3.50 in quarters, $3.70 in dimes and $0.30 in pennies(not zincs).