I've been getting into the habit of doing oil changes on my three hubs around this time of year, saves having to think about it too much and it's easier just to do them all at once.
Last done January 10th:
Ogre was a little overdue - 5,400km, about 30ml came out after adding 25ml cleaning fluid, double flushed.
Mercury was almost spot on - 4,700km, 25ml cleaning fluid went in, but could only get 23 out! also double flushed.
Airnimal folder hasn't been out much, not surprising as it's my travel bike and I haven't been anywhere... 600km, 25ml cleaning fluid went in, 35 came out, it came out so clean I didn't bother double flushing.
Also took the opportunity to give the non anodised silver hub a polish, I don't know why Rohloff stopped offering these, it's a very satisfying way to spend an hour, though I can never quite get it to match the mirror finish on the SON dynamo hub, maybe a different grade of aluminium?
That's most of my Rohloff maintenance done for 12 months, wish I could say the same about the derailleur bikes.