Mike, your choke selsection to some extent reflects how fast you shoot your targets. A couple of things to consider. Magnum shot patterns tighter than softer shot and your inner 20" pattern has all the smoking power; regardless of distance. Data I have collected tells me the outer ring to 30" has about enough pellets to scare a crow; targets escape. Using good magnum shot, my inner 20" circle is fully populated for all chokes except Skeet and Full at 25 yds. Skeet is on its way down by then and Full hits its stride from 30 on. The data shows that the inner circle thins with distance but the outer ring dosen't get much denser. Would suggest you check your chokes, 10 patterns each distance, each choke. Cut two circles, one 20" and one 30", hole in the middle. Place the 20' circle so it covers the denses part of the pattern, mark the center, check with the bulls eye for POI. Count your pellet distribution and see for yourself.
cheers
Ron