I've hunted with a few folks around Chicago that thrive on sites with heavy trash. . . and do very well.
They will hunt a 30'x30' area and sweep it in three different directions and somehow, will end up
with at least one or two old silvers. Their logic being that most hunters will move on to cleaner areas
after 30-minutes of frustration.
If you have a smaller than "stock" coil for your detector, you may want to try that to separate your targets
more effectively if they aren't running too deep.
From what you said about your site, (nails, bottle-caps, etc), there has been activity. If this is in a rural
area, "church" afforded one of the few times folks could readily get together socially in significant numbers
for picnics and other church-related events.
When it come to metal detecting, patience (or stubborness as you say

) can be one of your best assets.
Good luck!