Firstly, if you live on a dock
, Stainless chain is wonderful. If you live on the hook, forget it.
We have had our chain re-galvanized 2x (actually 3x as the first time was re-done)
We have been on the hook for 17 years now.
If you choose the highest grade of chain to have a high strength to weight ratio, there might be 'some' truth to the story about heat damage.
If you choose the heaviest weight to strength ratio it would make no difference to re-galv it 100x.
We get 6 years on our 330ft of 1/2" chain.
We do not swap ends, because that WILL result in a rustball in the locker.
The chain will not rust when in use, but when in storage
Saw a french boat once, his chain locker was a 20" pvc pipe. His kitchen sink drained into the locker, that greasy water running over it. When the bits of onion etc got trapped, they went over the side next time the anchor was used. His chain was never galvanized, and never rusted.
You can dump light oil
on the pile to help deny oxygen to the steel
So, short answer, 6 years of 24/7/52 use...