Just because of the layout of the course I play at most frequently, I yell more often than if I'd play elsewhere. A lot of parallel holes early and late in the round. Early... people haven't warmed up and are figuring out their swing (plus the second green is reachable from the tee and is directly next to the third tee). Late... people are tired (or not as sober as when they'd started).
I hit someone about two weeks after joining this club. He was walking out of the trees down the left side... I hit a quick hook... I yelled... he tried to jump over the ball and it caught him in the shin. Two days later, I almost hit someone else on another hole. It's made me very vigilant and a little 'quick on the draw' when it comes to yelling fore!
Have really sucked myself this year and am playing with players that are generally worse than the ones I played with at Kittyhawk, so there's a lot more yelling this year.
My new course (Miami Shores, Troy, OH) really only has a couple of places I regard as dangerous and that's only because of my tendency to hit giant hooks with irons. The greens for No. 2 and No. 12 at Miami Shores are pretty close to the tee boxes on the next hole. So when I snap over on one, that's where those suckers are heading. I guess a third dangerous place is a par five with a gradual dogleg right over the first 200 yards or so with pine trees lining the fairway. It easy to slice or push one into the trees and have it shoot out toward an adjacent green.
We know the drill, watch each other's shots and call out if there is a real risk.
2-3-2-2. I rarely have to yell fore, because at my home course, you’d have to miss pretty badly for it to be a danger to other golfers. When I do play with others, I play with golfers of all levels. We have at least one guy on our team per category in the OP.
My brother is in the bottom category. He doesn’t technically have a handicap yet, but he’s usually shooting around 50 or 55 for nine holes, so I’d say his handicap is 25 or 30. He doesn’t spray the ball, and nor does anybody else I play with, but he just chunks and tops a lot of shots. Luckily, there’s no hole on my home course where a thin would endanger others.