A few weeks back I uses Park and it sniffed out a few buttons at a worn out site and that got my attention. I wasn't sure if it was just the frequency range or something else. I hit another site today to see if Park could unmask anything in the iron and was really surprised when I pulled out a large cent. Pic below so Dan won't yell at me. I don't think I've pulled a copper from this site in several years. I am pretty sure it's the high iron filtering that allowed me to recover this copper. I had the Silencer set at 3 and the Bottle Cap reject at 5. I had the Reactivity set at 1.5 when I moved away from the cellar hole foundation. The other thing I did was switch to the XY screen. I hadn't used XY in years. That really came in handy as the bigger deep chunky iron would give a decent audio signal but the XY screen would call it out as iron.
The large cent gave a faint good tone with a bit of iron buzz. The XY screen indicated it might not be iron so I dug and was surprised when the 1819 Matron popped out. The other surprising thing was that it wasn't particularly deep at 5 or 6 inches. Usually when I hit a copper at a Reactivity of 1.5, it will scream at 6 inches. But I think all the iron near it and the heavy dose of filters surpressed the signal.
I've always been one to use as little filtering as possible but Park has shown me that a lot of filtering can be useful at times.