Wax-based lubes do not hold up well under wet conditions, but they should be adequate in dry weather. With less visible gunk buildup, bike owners may tend to clean wax-lubed chains less often than others, and this in turn could account for much of the difference in observed lifespan.
__________________
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069