I find I shoot best with rehearsed cadence. When I slow down and try to break each shot individual with the perfect sight picture my groups open up. When you use a faster cadence your muscle memory tends to take over. The grouping shrinks with the pistol returning to the same point of aim with natural muscle memory. This does not always hold true on real accuracy you may have a tighter group when you go faster just not as close to the center. Ex: 5 shots in a close group on the bravo compaired to, 2 on head alpha and 3 all over on bravo
Just my take.