does it matter how long it takes if you're going to do it once?

last month I moved 20 years of email

I started offlineimap before I went to bed and it finished before I woke up

> does it matter how long it takes if you're going to do it once?

I do it regularly for backups and updates. For an update I basically spin up a new server and then sync it. I do not want to wait that long, to see whether an update contained a bug or not.