Repetition as a positive aesthetic quality

[ololololo]

If they weren't fully engaged, or were getting 'tired', wouldn't you expect these types of repetitions to generally increase monotonically over the course of their work?

Not necessarily. He could have simply gone to rest, and then, inspired and with new words, returned to work.

In most cases, wouldn't scribes using vellum be copying from a prepared source, not actually writing the content?

Then it could have been the author’s mistakes.

Copying requires no creative energy, the amount of 'creative energy' to change words halfway through a copy vs copying the entire same word is marginal to nonexistent.

I meant that the scribe might have gotten tired of writing by the end and simply started cutting corners.