One dart can be good. Two darts can be better. More darts may be better yet. Only the normal restrictions of good design set the limit to the number of divisions of the dart control. Sometimes the amount of dart control is just too much burden for a single dart. It produces too great a bulge. It greatly interferes with the continuity of the fabric design. It throws a seam line very much off grain with straining and puckering of the material as . . .