Actually, it seems that these "settings" are done 'en masse. The Yamaha engineers may take a few bikes off the line and actually make some CO measurements on those, but then once they feel they have come up with some good numbers, they just use the same exact ones on an entire batch of bikes. Most are the same through an entire model year.
The first gens all had numbers that escalated from left to right. Folks thought that might have something to do with the restrictions of the air path inside the air cleaner. It wasn't until around 2008 that we started to see 10's straight across. Not sure why they changed it, but without having gas ports in each individual exhaust line (before the cats) it would be pretty hard to get any really accurate setting.
The first gens all had numbers that escalated from left to right. Folks thought that might have something to do with the restrictions of the air path inside the air cleaner. It wasn't until around 2008 that we started to see 10's straight across. Not sure why they changed it, but without having gas ports in each individual exhaust line (before the cats) it would be pretty hard to get any really accurate setting.