I can pretty routinely put repeated rounds well inside a 6" circle at 50 yards with any of my revolvers, open sights, including a snubbie, double action, 2 seconds per round, including reloads. I had an old coach that taught that. Example, 12 rounds in 24 seconds.
If I move out farther, it doesn't really seem to matter if I slow down or fire single action. The groups just get a little bigger. Once the target becomes difficult to see (100 yds plus) the groupings actually improve a little. I think I switch to "ball on post" sighting, using the entire target as the ball. My groups will be a little low, but pretty closely clustered. If I was making a critical shot at 100 yds, I could aim ball on post, then nudge it up just a smidge and probably get things closer to center bullseye.
I"m not a hunter so I can't say how any of that applies to hitting a deer/sheep etc.
Sgt Lumpy