IIRC, your hubs have sealed cartridge bearings, not the more common cup-and-cone, so there is little need to do any maintenance on them ever. Generally ride them until they get noisy or develop significant play and then replace the cartridges. I expect the rims will wear out before the bearing need to be replaced unless you routinely ride in very wet conditions.
Yes, cartridge bearings can have their seals removed, be relubed and the seals replaced but most rides don't bother.
As noted above, oil lube has to be renewed very frequently and has only an insignificant benefit.