It depends on what kind of driving you do. If you do all short trips of a few miles at a time and only rack up 2500 miles in 6 months, they you are right on. But if you drive 40 miles a day you should be fine going 5000 mile oci on conventional and longer on synthetic.
I always did 3000 mile and sometimes shorter, but now am running closer to 5000 mile. The motorhome gets whatever the trip length is, typically 4000+ miles.
I have an Aerostar which is on month 13 of an oci at 6000 miles. I plan to change at 7000 miles and run an oil analysis. The oil is Redline and it has taken over 4 quarts of makeup.