I have read to the bottom of this long thread. Good information in many places, particularly the longer responses. Thanks all!
Based on my 18 months of experience, the recommendations for VERY clean chains to start are critical. I have been very happy with cleanliness and durability when I got the chain clean first, but not when I failed to get the factory lube off, as evidenced by mucky black stuff after a few rides plus noise. I’m about to clean a lightly used chain I almost gave up on for that reason, and will follow cleaning advice here carefully!
A tip on reapplication: to get the wax between rollers quickly, I backpedal the chain in a small gear a good 10 plus revolutions while tapping the side of the chain with the bottle. Tapping works the wax emulsion off the outer surfaces of the rollers getting it underneath next to the underlying pins (visually at least, little is left on the surface).