A few years ago, we ran large ground wires from a service to the rods and water lines. Then, the large ground wires were only run to the water lines. Now, everything is a #6. I know where a thousand dollars worth of copper can be reclaimed and replaced with a couple hundred dollars worth.
It's hard to have respect for the rules when it is so clear that they are just a whim.
10-812 The size of the grounding conductor connected to a grounding electrode conforming to Rule 10-700 shall be not smaller than No. 6 AWG.
Appendix B: It is intended that the size of a grounding conductor for a solidly grounded alternating-current system connected to a grounding electrode need not be larger than No. 6 AWG. The majority of fault current will be taken by the service grounded conductor of the system back to the source, and a grounding conductor sized not less than No. 6 AWG would be sufficient to carry any portion of the fault current that will flow through it.