Great article on the history of targetry. For the tactical types, check this out:

U.S. Cavalry troopers were required to shoot dismounted, single handed, at 15 and 20 yards on the Army Target "L". After they qualified on foot, they would then repeat the course of fire, this time astride a horse at the gallop.

Those complaining that competition and bullseye shooting doesn’t take real world concerns into account do so from their ignorance of what these events actually are and can be.

A Short History of American Target Development and Evolution
by Hap Rocketto

The evolution of targets continues to meet the needs of the competitor measuring his skills. Double Distinguished Smallbore Rifleman and noted shooting historian Paul Nordquist mused that, “The target is a measuring device one used to measure the abilities of a shooter. As with all measuring devices you pick the one most suitable to the task. No matter which one you pick there is an element of arbitrariness involved.”

With that in mind, and with all of what has been said about target development and evolution, there is one constant through all the years of organized competitive marksmanship in the United States. The object of the game has always been to hit the center of the circle. Dimensions of the target and aiming black, width of the rings, or the distance at which the target is engaged matters not. What is important to remember is that the target has almost always been a circle and, no matter what size the circle, the center is still the center.

Read more:
http://www.ssusa.org/articles/2015/7/5/a-short-history-of-american-target-development-and-evolution/