I also have a particular interest in this thread, following a question to Buck Brannaman about four years ago at a clinic.
I told Buck that I spent time studying Dr. Deb's writings from Eclectic Horseman and online. Then, I asked Buck if he had anything in his usual riding practices and development of a young horse, to address "Long and Low" in particular.
Buck told me that no, he was not trying to directly address "Long and Low" in particular in his riding of a young horse. And that I should go ask Dr. Deb when, how and why I would do that.
So, I am understanding a few things:
First, that it is easier for a horse to raise the base of his neck from a long and low position. (From the 2015 thread)
And second, that the important thing we are asking of the horse is to turn loose, to give over, to release any brace in his body but over his back in particular.
And Buck absolutely teaches his horses to raise the base of their necks, and he is All The Time asking his horse to give, to release, to turn loose.
In my own riding, my horses tend to volunteer a nice neck telescoping gesture when we are long-trotting for a few miles.