Edward,
In a decade plus here, I don't think I have ever seen the concept of shared tees discussed, so congrats on bringing up an original topic, at the very least.
Interesting thing about shared tees. I love them, have designed them (including one on the drawing boards just last night) and defend them. But, there are problems, depending on layout, that do occur in the real world. Safety, waiting on others, noise, and even confusion and playing from the wrong tee (which in competition would be disastrous to score). Lastly, at some cost conscious period of time a superintendent might wonder why he is treating an unused connector area as a tee, thus adding to cost. (there usually is some unusable space on those things)
It would be interesting to know if any of those events occurred at Seminole. Sometimes, I think the current wave or restorations simply forget the practical matters that caused the changes in the first place.
Not the best analogy, but I recall a project in Vegas, where a young landscape architect was proposing all sorts of trees. A crusty old landscape architect pulls me aside and tells me that he tried those same trees before the other one was born, and they would never work long term. Yes, there are new varieties, and yes, irrigation is better, but in the end, its one hot/cold season that is stronger than all those tools to push borderline plants. The younger LA simply hadn't been around long enough to know the long term effects.