Well, if you've used a box and whisker chart, you can see that it's incredibly useful for showing range and spread of data. But even if you haven't, four is still a pretty good number. After all, people can internalize what it is to be in the best or worst quarter, but ask ...
judging wind speed, direction, and angles. Most people use the aiming dots on the reticle to hold off for wind, meaning they don’t usually fiddle with the windage turret. Shooters call this the Kentucky Windage method.