Actually, there has been no HINT given. Everyone has responsed to my question of time by citing how many miles they got out of their steel bolts. Mileage has nothing to do with it. I could build a bike and leave it sit i my garage and never ride it one time and it will be just as susceptible to galvanic reaction (minus the salty sweat drops).

Mileage is irrelevent. If you put 30,000 miles on your bike in 2 years, yeah I would expect the chainrings to wear out before galavanic corrosion set in.

If you put 1000 miles a year on your bike and want it to be in good condition 20 years from now, totally different situation.