I was going to mention, it seems that Dr. MacKenzie's thoughts on par 5 holes was opposite to Flynn's and Crump's. Holes like 13 and 15 at Augusta National, for example, were intended to play as 'half par' holes, that tempt golfers to go for the green in two, right. Then, the 8th holes at both Augusta National and Crystal Downs came to mind.
Having seen the hole in person, I can't believe the pros can reach the 8th green at ANGC in two! It's amazing. Not only is the hole blatantly long, it plays DRAMATICALLY uphill. And thus, the natural cant of the fairway leaves a severe uphill lie no matter where you drive the ball. To play a shot from that type of lie, more than +/- 230 yards, uphill requires great skill.
Eight at Crystal Downs is a tough three shots - at least for the layman. It's a blatantly long hole, too, but I think the principle challenge is derived from the fact that it's very difficult to find a level lie anywhere through the green. The fairway is naturally 'lumpy', all the way from tee to green. And the putting surface there, is very small. I wonder though, what Woods, Els, Mickelson, et.al. could do there, in regard to reaching the green in two? It seems unfathomable. But those guys have surprised me before!