Too factors to take into account besides saddle height. Crank length and the geometry of the bike is important for each individual body as well as gearing choices to get the best possible advantage for their riding conditions. Just look at the TdF coverage and I doubt you'll see any of the riders with a fully extended leg at the bottom of their stroke while in the seated position. Even with a "proper fitting", the individual may consider that a starting point/baseline and make additional adjustments or change equipment to best suit their riding style and comfort level. A few millimeters either way can make a major difference.