Hal I agree they do all contribute but at 120 volts not to much.
The Code uses 25 ohms as a reference for a minimum for one rod or you need to toss in another one.
Lets say all the electrodes together get you down to 8 ohms of resistance.
At that level of resistance a fault (not including the neutral) will draw 15 amps.
This will take a long while to trip a 15 amp breaker if ever.
The electrodes contribution will be a very small percentage of the total fault current once you include the neutral.