When you take a look at the cams, you will see that the marks on the cams dont align with the center of a tooth. The marks on the belts should be similar (not aligned on the tooth center). When I counted teeth on my new belt, it was pretty much spot on the 0.8 teeth and 0.6 teeth. I have heard of some gates belts where the marks were off. You dont need precision of down to 0.1, but as long as you're not off an entire tooth I would think you're fine.
if you havent already seen, I did a short writeup on my belt install on the 2010x.