Back in the '60s during grad school, I was hunting quail in southern Ohio and a covey took off just in front of me. I followed a bird and my sights came across a classmate's head--just stopped in my tracks and did not fire. I will never forget that.
I had a similar experience the first or second time I went hunting (12 or 13). Four hunters in a line, unsuccessful pheasant hunting I believe, one of them an "observer" lagging, several rabbits broke from brush. When asked why I didn't shoot, they were in my zone, I explained ---- was in my vision. They figured I got "buck fever", I know better. You have to know where the people and dogs are.