It really doesn't matter if they can reach the group ahead with a 1 in 20 shot or a 1 in 1,000 shot...Don't hit the shot until you know you can't reach them with any percentage.
I don't care to make the speech that starts "I'm sorry I hit you in the head. I had no clue I could hit the ball that far."
Yup. A much better speech is directed at your playing partners and goes, "I probably can't reach them but I am going to wait."
I don't think things like that really effect the overall duration of a round. When the course is crowded a little extra wait here means a little less wait there. The problem is that watching someone whose actions are inefficient and silly can cause irritation even if they aren't truly affecting the overall speed of the round. Like the guy who leaves his chipping club on the far side of the green away from the carts and has to walk all the way over there, wasting time and taking longer than necessary to clear the green. But then his group has to wait on the tee for the next group. While he delayed your group's shot to the green he really didn't make the round take longer. But it is irritating, nonetheless. I almost have to just not watch the group ahead so that this kind of nonsense doesn't get to me,