I do mine every 6 months but with a slight twist. My Greyhawk is on the road for 6 months then sits for 6 months. So when I return from travelling I change the oil and filter. Then it gets parked for 6 months. In the fall I change just the oil and use the same filter.
2012 Greyhawk 31 FK
Flat towing a 2008 Miata.