I think you just don't hear a lot about it, and people don't acknowledge it much in themselves, because of the stigma/demonization of multiple personality disorders. For me, as long as I(we) can pass the Turing Test of Normality, I don't really mind that my brain works the way it does. If anything, I quite like the way it works.
At the moment I learn something new it just snaps into place at once and the knowledge is integrated on the spot.
Also English is a foreign language for me and the same goes for my native language. Whole concepts emerge as I'm trying to do or say something and then I have to put them into words(in either language).
Sometimes the process of talking is excruciatingly slow and interferes with my thoughts. I find that I can type a lot faster and that helps a little.
I'd also bet that the first "human-type & human-level" AI will be quire insane by human standards at least if we don't get this inner attention focusing part right from the first time. Considering that this insane AI will also get super-human pretty fast, I'm pretty scared of what it would do before it gets itself to some sort of inner equilibrium or "sanity"...
We should probably make that internet uplink mostly mirror-down libraries only.
This is something that can happen via psychedelics or meditation. I don't know of any way to predictably induce it though.