I understand the need for distance when placing rods what I'm saying is there should never be an exception to your resistance.It is more for lightning and radio frequencies. Think of a large energy entering the ground rod at the ground level and traveling in all directions at the speed of light creating a half sphere. Having two rods the two fields will overlap and be out of phase with each other due to the wire length feeding the ground rod.
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once you meet your desired resistance rating you can then test for loop impedance to work out how big your cable size needs to be, at least that's how I was taught.