I think the OP may be thinking that because you draw the standard 40" circle for all choke constrictions that they are all shooting 40" patterns. If this were true you could use a cylinder choke for everything out to 60 yds. Obviously this is not the case.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli