In 2014 when I rode Pacific Coast, my riding partner started with a waxed chain that he waxed at home with paraffin wax. It was quite noisy after several hundred miles. We did 863 miles (Astoria to San Francisco), but I remember his chain as being very noisy several hundred miles before the end. That was over a decade ago, I can't say when it really started getting noticeably noisy.

Given Gauvins experience cited above with a quiet chain at 500 km, that suggests that the type of wax used could make a big difference. Gauvin's quiet chain differs quite a bit from my friend's experience with paraffin.

I am sticking with a conventional wax based lube that I add to my chain when it gets noisy. I pack much heavier than Gauvins on a bike tour, but I would not carry a spare chain on a tour. That comment surprised me. I carry a spare quick link or two, plus a couple extra chain links, that is all.