I guess its a chicken and egg discussion.
Found this article that backs up some of what you are saying Bruce. However it talks about stringing caused by choke patterns, shot deformation due to charges and soft material. I find it hard to correlate that load shape like the British discuss in squaring the loads. Would object of squaring the load suffice regardless of choke patterns, charges and material in itself make things pattern better, or does addressing the those issues just get close to a square load. Btw Bruce does Brister mention square loads.
https://shotgunreport.com/2014/04/29/shot-string-2/