-tion for -the, and vice versa, slip past my censors.

Did you know typists type faster than they read? If you make a typist type word for word, by presenting the text one word at a time, the output slows drastically. There seems to be a significant "look-ahead buffer" that is essential for maximal efficiency.

A little like reading itself, I suspect: phrase-by-phrase is much faster than word-by-word. (Don't even _think_ of letter-by-letter.)