Or the fact that the task is so mundane/boring/annoying/irritating (pick an applicable adjective) that it's worth it to you to spend a day automating it so you never have to do it again.
Great point - the benefits of automation can't always be reduced to time saved per operation. I wrote a blog post [1] about this in response to that xkcd.
https://xkcd.com/1205/
On the other hand, sometimes you're automating for reasons other than time savings. Maybe reproducibility or auditability.