A random thought occurred, how do you think they work in lore? Do you read some sort of magic words that put the spell in your hand and if so then why can't you remember the words and recite them again? Multiple scrolls of the exact same name and magnitude implies that they contain the same information so what would stop someone from reciting the words more then once?
This may sound stupid but it doesn't make sense to me so I'm curious if someone can make some sense out of it.