I don't think it is of that much importance, use the speed you are most comfy with! As you have seen here, you get the whole spectrum of speeds. I personally turn and sand at high speed (I don't even know the rpm's of my lathe, but I used the high-speed setting of the belt), for application of either Enduro or CA I turn the speed down to 200-300 rpm's or so. A big advantage is a variable speed lathe, though - no need to change belt settings!!