Roy Smith wrote:

A normal 5-speed single-belt system spanning the same range of speeds is
just as useful and a lot easier to use. There's no speed setting chart; if
it's too fast, move the belt up. If it's too slow, move it down. Simple.
Even I can figure it out. I can't think of any job where 900 RPM wouldn't
be just as good as 840 or 1065 RPM.

I agree, but pay attention to the SLOWEST speed.

I find really slow speeds to be more useful in woodworking than more or
higher speeds. The slowest speed on my DP is about 500, and I often
wish for something much slower, like 100, when using large forstner bits.

Rarely do I use anything over about 1500 in woodworking. Other crafts
use high speeds all the time.

Barry