Earlier this year I marked off a 5'x5' square within the trashiest pull tab area of an old park that is now closed to the public. Using two different detectors and three coils I cleaned out every high tone from every direction in those 25 square feet. Every high peep. I found about a dozen coins. But, those aren't the coins in the photo.
The attached photo is what I dug from my "pounded" and "hunted out" 5'x5' spot AFTER I started removing the shallowest, strongest pull tab signals. A few extra tabs would come out with each one I targeted. The coins in the photo were either found with a pinpointer while removing a pull tab, or were unmasked and gave a high tone when I rescanned with the detector.
I only kept going until I found a "proof of concept": A coin that was notably deeper than the 2" to 5" deep pull tab layer. In this case, it was a 1920's wheat penny. I also didn't want to lose my mind intentionally digging pull tabs. Indeed, I had probably only dug 10% of the pull tabs in that square. No doubt more coins left behind, too. I've done the same thing on other hunts and found silver, but this was the only time I thought to take a photo of the coins with the pull tabs.
For what it's worth, this isn't how I normally hunt. But, I am willing to experiment. It's not a bad idea if the immediate area has proven itself already, or if you want to "survey" a 3x3 or 5x5 area just to satisfy curiosity. If it's a good large property you're better off spending time covering more ground. But, there's clearly something to be said for digging out shallow trash signals if you've hit a hot spot of coins.
If nothing else, it shows why trashy parks keep producing oldies.