This may work for the initial fitting, but that is a relatively one. Some of the later fittings, particularly in the shoulder areas are more difficult and more trial/error.
Unless there is actual customer preference involved this is probably an area where more highly accurate measurements + a better formula + better construction could make this much faster. For people it's easier to fix it after the fact than do more up front calculations, but when a computer is finding the solution they can probably get vary close the first time.