Top of Page 14. A,L,R,S,X have little meaning because there is no standard of measuring flex with in the golf shaft industry. Many mid to high handicappers find it much easier to hit fairway woods than long irons. A more flexible shaft will increase distance, but may sacrifice some accuracy if to flexible for your swing speed and tempo. A stiffer flex will help a with accuracy but will sacrifice some distance if to stiff for you swing speed and tempo.
Most average golfers play with too stiff a flex reducing their potential distance.
Recent studies have shown that torque ratings can play a big part in shaft selection. Shafts with low torque ratings have higher torsional resistance. This means that the shaft twists less and consequently the club face tends to stay slightly more open. This is usually helpful to golfers with a slight hook or draw. This is helpful to golfers with a slice or fade.