Considering how cheap it is
I change fluid in ALL rides once a year. Car Truck, Bike, Plane, The moisture in it is what I fear and don't think that it's sealed so it can't take on moisture, brake fluid is hydroscopic. Hey it's cheap.
I change Auto tranny oil in cars and trucks every 2 years. Oil in manual trannies well I had 200K on my dodge PU but it had syn tranny oil.