[rendall]

> 'I think the more logical explanation is that the deleted texts were considered worthless.'

It's your contention that the monks had unlimited access to parchment, but just chose to overwrite older work?

> If the monks were isolated then why should they copy books, especially when they had to delete older material to do so?

A religious order dedicated to copying books as a spiritual discipline isn't going to just sit around when parchment is hard to come by.