Do you impose a limit on yourself when it comes to how many you won’t shoot at?
It’s difficult to prove conclusively, but to me, if you bang into a flock of say, 50 birds, the 48 survivors are less likely to return to the field, than if you did not fire at them at all.
I have seen decoyers set up without first clearing the area of resting birds, then fire into the entire feeding population of maybe 500 pigeons when they came in en masse.
“Can’t understand it” they say, “fired two shots and didn’t see another bird all day.”
Obviously, there is no hard and fast rule as to how big a flock I would leave, but certainly at the beginning of a day, I would be reluctant to scare more than 30 birds for the chance to kill just two.
That is why we try to choose windy days on which to shoot, so flocks are more likely to become fragmented, and also try to arrange things so that we are not shooting down the flightline, again, so as few a birds as possible hear the shots.