As a Southerner, I grew up hunting deer with buckshot.

Early on I learned that maximum buckshot range was the distance I could get a minimum acceptable pattern with the particular gun/choke/load combination used. That might be 20 yards or it could be 60 yards.

Your pattern board will not lie to you!

Here is one of the better examples I've seen of establishing minimum pattern = maximumum range for deer hunting. In this case a reduced recoil 8 pellet 00B load was the choice for hunting with a 14" barreled firearm. Post mortem wound damage shown was extensive for the three deer taken on this Canadian hunt.

Indeed, the lessons for buckshot defensive use as well as hunting are valid.