We have discussed this before, but another reason for more acreage is not only cart paths between fw, but cart paths between green and next tee. Even if behind the green, it adds 10 or more feet to the distance between the two. And if you have parallel holes with the next hole playing right back you have to keep the cart path about 50 feet to the side of the green, but also keep an eye out for the play coming off the next tee, so where tees used to be as little as 175 feet from the center of the previous green, they now are at least 200, just because of the need to keep a cart path out of play.
There does seem to be a real disconnect in this, because as mentioned, there are lots of courses tighter than the scientific explanation where the hair doesn't raise up on the back of the neck. I propose the "hair raise" test as a legal standard. If the hairs on the back of my neck stand up, I think the green and tee are too close! In reality, I think the angle is as important as distance in being safe and feeling comfortable.
From the USGA charts, 2/3 of average players miss within about 7.5 degrees each side of the target. On a 265 yard tee shot, that is 80 ft each side of center.
Hurdzan once told me that he sent out associates to measure actual tee shots in proposing 15 degrees. Nugent had us do the same thing years ago. From memory, we both agreed that over 90% of balls land within 150' either side of center, and typically travelled about 190-200 yards. That comes out to 15 degrees at 200 yards. At 265, 15 degrees translates to 220' either side of center, wider than most actually use for design of housing corridors. That angle is really for off line shots to adjacent areas not at full length shots, and its questionable whether a shot hit that far laterally could ever attain full distance anyway.
A lawyer would tell you we are only resposnible for avoiding clearly foreseeable safety situations, not providing absolute safety.
However, I doubt any lawyer would suggest 90% constitutes "Preponderance" of shots not being dangerous. They would argue for 99.99% if their client had an eye put out. There is no evidence that I know of to suggest to what degree (95%, 99%) any extra safety buffer distance achieves.
KN had a copy of an old court case where the expert had testified that 22.5 degrees was the maximum deflection on a golf shot. On a 265 yard shot, that translates to 330' either side of center, so Tom Doak must have witnessed one of the maximum misses of all time! A friend whose house was getting pelted once asked me to look at it. In measuring the locations of ball strikes on his side wall, I will be damned if the very last one didn't measure out to 22.5 degrees.
So, for adjacent tees and greens, I actually plot out 25-30 degrees in routing, figuring if the cart paths, etc. get added in, they will put golfers no less than 15-22 degrees in the next line of play. It does add space, but I never feel unsafe when I play my own courses. It also allows for the inevitable day when someone adds a back tee, which often decreases the planned safety angle.