Reno,
The point that I was making was that the EGC could actually be a _source_ of a shock if the _local_ ground potential at the hot tub is different from the _local_ ground potential where the building electrical system grounding electrode is located. I don't see further grounding the electrical system as offering any sort of performance benefit; instead I see this as 'bonding' the earth at the hot tub to the same grounding electrode system as the water in the hot tub.
I was thinking in particular of this thread
https://www.electrical-contractor.net/ubb/Forum1/HTML/003127.html where the customer was being shocked between a bonded water spigot and the wet ground nearby. The voltage to ground at the spigots was present even when the main to the house was off. The problem was POCO neutral current going through the earth.
-Jon
