Chain wear is a complex issue. Some chains wear by elongation that can be measured with a precision rule and others like Campy chains do not. Some chain wear gauges add roller wear to elongation and give exaggerated results. Campy recommends measuring between the outer plates to a length of 132.6mm before changing chains. That measurement is a mixed bag of elongation and roller wear.
The idea that new lube, applied after chain cleaning won't penetrate properly is nonsense, but if a water based cleaner is used, the water must be removed before lubricating. I use naptha/white gas/camp stove fuel and allow a full day for the solvent to evaporate, but my wax lube uses the same solvent to dissolve the wax. I use several chains in a rotation and usually switch to a fresh chain about every 500 miles.