We're all aware of having too many fingers inside the guard on two or three trigger (not often) guns. I tried it when a kid, with my Baikal 12 bore O/U
and got a bad cut in the middle finger(back trigger) from the back if the front trigger. It was rather sharp and cut right to the bone above the first knuckle.
That's never happened a second time. I "pull" only with the index (first) finger.