One would have, but there are also cultural barriers to consider. I'm no expert on late medieval or early renaissance Italian culture, but what amateur reading

One would have, but there are also cultural barriers to consider. I'm no expert on late medieval or early renaissance Italian culture, but what amateur reading I've done paints a picture of a culture where the nobility may have been literate and able to write letters, but serious writing such as creating vellum books was still considered dull, dirty, grueling work that was beneath their station. Henry Darger (who was, IIRC, a janitor) was mentioned elsewhere in the thread. I think that you might get a more culturally comparable example out of the idea of Sarah Winchester whiling her time away in a manner more akin to how Edward Leedskalnin did.