I think that the nourishment of the metal detector operator has been overlooked here. Many metal detector enthusiasts, after years of obsession have taken their ugly toll, are badly malnourished, and easily winded by the slightest grass resistance on the coil of their metal detectors.
The value of a good metal detector and experience using it cannot be underestimated, also do not overlook the value of a properly fed individual, with plenty of B vitamins surging through the vasculature of your liver, so that you are not dizzy when your heart beats like the tom toms of a village of maniacs as you dig from the earth your corroded prize.
Ah hope this helps!