Gunnar, like I said...While others will complain about their sites drying up, the truth is that any old machine can make a dead site come back to life and give up some great finds that everybody else missed, just by digging the signals nobody else will dig. Just removing the non-ferrous "trash" people will find some great stuff, not to mention silvers that were masked under them. 99% of hunters won't do that. They only look for those silver signals. Well, some of us do dig the trash to see what it is and what might be under it, but usually only for an hour here or there where as you seem to make it your mission all day long.
Then there's also you digging dead straight iron signals. NOBODY does that. I bet less than 1% of all hunters, besides relic hunters of course (some of them) will dig iron signals to see what they might be or what might be under them. And as we all know iron seems to be the #1 target at most sites. Imagine how many silver coins and other great finds you don't even know are there, as you walk over them and only get a null or an iron signal and never a coin hit and just walk on by. No machine can see past the first thing it hits. That's just the reality of the nature of detection fields and the laws of physics that relegate them. For that reason, even a tiny piece of iron will completely mask a deeper silver coin. Even a silver coin a good bit off to the side of it but is deeper than the iron. If any part of the field hits that iron first it's game over, and we all know detection fields are broader the closer they get to the coil, so the deeper the coin and the shallower the iron, the more off to the side the coin can be and you'll never know it's there. You'll only hear a null, or just the iron if you don't have that discriminated out. And that's only talking iron here, not even mentioning how many coins and other great finds are masked by shallower non-ferrous junk. Just think of all the 60's era round pull tabs that are masking deeper silver coins and other good finds.
That's why tiny little trash coils are such a good choice for heavy trash, and also why griding a site from at least 3 angles (actually by my count 4 at least....two 90 degree angles, and then two opposing diagonal angles like an "X") is the only way to really unmask as much as you can, and even then there is still more that no amount of angle hunting will ever unmask until you dig up the non-ferrous and ferrous (iron) junk masking it. No way around it, some coins will never be seen until you dig out what is keeping you from seeing them, and they don't have to be right under the junk either. As said, that all depends on the depth distance between the coin and the shallower junk. The further distance in depth between the coin and the shallower trash, the further off to the side the coin can be. Picture a detection field and you'll know why, as that field is broader the closer it is to the coil, and it's going to pop with the first item it sees and warp around it like a moth to a flame. That's just the nature of these fields being generated.
So I say dig on my friend, and you'll still be finding good stuff while others have long since moved on to other sites or other hobbies...