I know a guy that does. He does Iron Butt rides all the time and does 14k on his BMW GS with Rotella T6. He usually swaps the filter though halfway through. He has 90k miles on it so far and so good.
Honda says 8000 miles on the water cooled engines.
Seems like a lot to me.
That's with convetional oil.
Few go that long even with synthetic.
Some engines are harder on oil that others.
SO the answer is: It depends.
This guys goes through a BMW every 4 years he rides so much. Must be nice to have lots of cash and no job. Last year he did the trans Americas ride from Alaska to Argentina and back on a dual purpose Suzuki.