I agree, every 2 years should be sufficient. But depending on the conditions, cold, dirt, stored outside, etc. Yearly might be better.
Also I prefer to change the oil at the end of the season, before going into hibernation with possible moisture, acid, or depleted corrosion inhibitors sitting in the crankcase.
Something else I've picked up on, the new automotive oil doesn't have the zinc additive like it used to. It's been removed with the assumption most new engines have roller cams and it's not needed.
Diesel engine oil still has the zinc additive. That's what I use now in everything with flat tappets.