Some of it has to do with the wood itself. Some species are much easier to machine than others.
The chips that come off of the cut will tell you a lot, but again varies by species.
You really want to minimize the dust in favor of shavings. It takes some experimentation, which is the reason for the range in the charts.
It is just as possible to go too slow as it is too fast. It is probably best to start at the low end of the chart and work your way up, to see if it gets better.
Feed rate goes along with this too. Moving too slow is just as bad as spinning too fast.