Aren't both inner & outer surfaces of the bush permanently lubricated by the grease sealed-in upon chain assembly? I.E. the outer surface of the pin, the inner surface of the bush, the outer surface of the bush, and the inner surface of the roller -- are the greased & sealed interfaces (rubbing surfaces).
The chains rollers (outer surfaces) are, then, (ideally) not rubbing surfaces and external lube may, when applied, offer a protective film and a pressure cushion to the roller sprocket interface.