well, it depends from brand to brand. Personally i think a semi good oil and frequent changes is better than expensive oil and less frequent... and good oil with frequent changes the best (obviously).
I would change oil less and less frequent as the engine starts to wear in, until your rings start to get crap seal and you get alot of blow-by contamination of the oil.
So change your oil every 10 hrs, but when you change, take note of the colour of the oil and the amount of metal fragments. If its still a pretty tranparent and browny gold then you could have left it for a little longer (still put some fresh stuff in tho). If it comes out black and with alot of shaving i would make the next change a little more frequent.
It also depends on how often you start your engine from cold. If your only doing 5 min rides you will be getting alot of blow-by with the cold engine and crap ring seal, so you will need to change more frequent. If you start it one and ride all day you will probably be able to delay the oil change as the engine will remain warm and result in less blow-by contamination.
keep an eye on these two things and you should be able to get to know when your engine will need a change.