As far as no par 5, Elie in Scotland is 16 par-4 and 2 par-3, par 70 (if I remember it well./
I think that this discussion on breather hole and routing is great.
To me, I like a breather hole because it can give you momentum after a bad start, or can kill momentum if you play it bad and make bogey.
An example of breather would be a par four in the 360-370 range where there's seamingly no pressure of the tee, maybe a simple bunker, it would seem that when you get on the tee, you know you'll have 9-iron/wedge to the green no problem. I don't see driveable par 4s as breaher, unless they are really simple, because your mind have to take a decision, and dramatics are invloved out of decisions (to be or not to be)
As for routing, it's very subjective but I also think that you see what you want to see out of a routing. If you're looking to built a course where the Tour will come in 2-3 years, you're not looking the same way at the piece of ground in front of you then if you're trying to built a 6500 yards second course for a club.
At Sagebrush, if the owners insisted to have a walkable course, the course would be shorter, would not go to where the 12th hole is, maybe would not go down to 7th green and 8th hole. If you compare the virtual routing with the actual one, which is best
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Routing is really, really key on a great piece of ground, but what you do with the holes is just as important on a site where you have to move a lot of dirt to have golf on it.