Indeed, this is talked about thoroughly in Getting to 18, in the chapter on Pacific Dunes. Crossovers are hard to pull off, because finding two greens and two tee positions close enough together to do it seamlessly is difficult.Pacific Dunes makes two crossovers: 3-4-12-13, and 4-5-11-12. That was the key to having holes run along the coastline both north and south, but using the coastline in the best way possible. [10 and 13 were far better playing to the north, and 4 is far better playing to the south.]
It took me six months to figure out that was important to do, and then a little bit longer to find a way to make it work. For Pacific, the last piece was finding the green site for #3, which was inaccessible because of gorse until the fire. [Previously, the routing had played from #3 tee to #12 green site.]
It's a decently long walk from 3 green to 4 tee, broken up by the halfway house, but also by the beautiful oceanfront view along the way. It's also a decently long walk from 11 green to 12 tee, only because we can't trust golfers not to play down #4. [When I play Pacific Dunes I usually just tee off for #12 from the back of #5 tee -- the hole is just as good if not better, as long as everyone agrees not to go down #4.] But those two walks were what made everything else fit together just right.
Most oceanfront courses cross over once, so that you have the water frontage on the right for one nine, and on the left for the other nine [as Pebble Beach does, at 3-4-16-17]. Most modern courses [a la Casa de Campo] hide the crossover at the turn so you don't notice it [and so you'll forgive the longer green to tee transition]. Whistling Straits has a crossover within each nine as well as at the turn, which Mr. Dye could make happen because he re-graded the whole site, instead of having to deal with natural green sites.
You often find good green sites close together, but unless there is a compelling reason to make the crossover, it's generally smoother not to. So, not that many of my courses have crossovers:
Do Cross Over:
Stonewall Old [10-11-17-18]
Stonewall North [10-11-17-18
, at the road - never noticed it's the same!]
Lost Dunes [sort of, as you go through the tunnel from 7 to 8]
Barnbougle Dunes [at the turn]
Sebonack [3-4-9-10 and 10-11-16-17]
Dismal River [at the turn]
Tara Iti [off the 3rd & 5th tees, and at the turn]
St. Emilion [1-2-17-18 hidden by road crossing, also 14-15-16-17]
Streamsong Blue [crosses the Red course twice, but does not cross itself!]
Don't Cross Over: High Pointe, Cape Kidnappers, St. Andrews Beach [which intermingles with other holes but never actually does a crossover - I had to think about it], Stone Eagle, Ballyneal, Old Macdonald, Rock Creek, National (Gunnamatta)