Retailers that excel in neither convenience nor variety of merchandise tend not to be very successful  Yet many successful retailers excel in just one of the areas and meet competitors' standards for the other
Hence, a retailer' s success need not depend on excellence in both areas
Runners who have only average speed and endurance are unlikely to win long-distance races. Some long-distance champions, however, win by being above average in speed or endurance only; ttherefore, being above average in both speed and endurance is not necessary.