After initial miles all well lubed bike hubs run in an oil path even if greased. It's my understanding and observations that the balls will plow a path through the grease as they orbit. The pushed aside grease will feed the oils that really are in play at the contact points.

The oil ports and nipples in some older bikes were for oil injection as I've been told. Seems the long lead times between bike production and the eventual sale allowed the grease to thicken , having an oil port would let the shop to add a few drops of oil to the thickening grease. As both lube technology and market efficiencies have increased this need to freshen up the bearing lube is far less. Assuming that the manufacturer uses enough grease when they first put the bearings together. Andy.