Yesterday a fellow shooter was missing targets at a match. He was using a Weaver style of stance and he was going seriously low left on the second shots on paper.
At first I asked about how much trigger finger he was using. After looking at him shoot it was clear that it was his stance.
When shooting the weaver the Push-Pull forces are added to the force of recoil and coordinating the muscles at high speed is difficult. This become even more difficult if there are arrays of targets. It takes time to tense and relax muscles.
By using the isosceles there isn’t a push pull and tense and relax but only forces against gravity and those required to hold and aim the gun.
So, by having a solid and relaxed stance and only using the muscles to defeat gravity, the speed of shooting is no longer limited by the time it takes to tense and relax muscles.