You may think you haven't heard The Typewriter, but I bet you have! Wikipedia:
The typewriter was modified so that only two keys work to prevent the keys from jamming. According to the composer himself, as well as other musicians, the typewriter part is difficult because of how fast the typing speed is: even professional stenographers cannot do it, and only professional drummers have the necessary wrist flexibility. It has been called one of "the wittiest and most clever pieces in the orchestral repertoire". Author Steve Metcalf has written that "Despite the almost total disappearance of typewriters in everyday life, the statistics show that "The Typewriter" is still a favorite Anderson item." The typewriter is considered a percussion instrument, and the typewriter part is usually performed by a percussionist or drummer, or rarely by the conductor
The claim that the typing speed is too fast for typists is directly quoted here by NPR. Perhaps a reflection of the consistent force required to make loud, satisfying clacks in concert than speed per se? Anyway, I don't believe it.