In poetry, by and large, one syllable out of every two or three has a beat on it: Tum ta Tum ta ta Tum Tum ta, and so on. . . .
In narrative prose, that ratio goes down to one beat in two to four: ta Tum tatty Tum ta Tum tatatty, and so on. . . .
In discursive and technical writing the ratio of unstressed syllables goes higher; textbook prose tends to hobble along clogged by a superfluity of egregiously unnecessary and understressed polysyllables.
Ursula K. Le Guin,
"Rhythmic Pattern in The Lord of the Rings"
The Wave of the Mind (Boston: Shambhala 2004)
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Yet another reason to hire literature students!