With regards to descrim and depth I always operate as lower discrim as my ears permit. On my land that's between 3 and 5.5. At the lower end I do dig some deep iron but that's part of the game. The difference the discrim makes is whether that deep hammy (or other low conductivity item) makes an iron sound or a dig me sound. I'm sure it makes little difference to high conductivity targets like pre dec pennies, etc.
Just remember if 49 in every 50 'coke' signals is coke and the other one a hammy that's not too badder odds!!
Good luck, V
