The thing is, though, that time wasn’t wasted. It was spent fully understanding what they were actually trying to say, the context, the connotations of various different phrasings etc. It was spent mapping the territory. Throwing your initial, unexamined description into a prompt might generate something that looks enough like the email they’d have written, but it’s not been thought through. If the 10 minutes’ thought spent on the prompt was sufficient, the final email wouldn’t be taking days to do by hand.