The best use cases for me have been when I'm stuck trying to word something in an email to a customer or in an internal presentation. I give it a prompt and the results are usually good enough to get my own thought process going.
I also write a fair number of scripts just to do some data analysis and chatgpt saves me a bunch of time that would have been spent looking over stackoverflow posts.
On average, I'd say it saves about 2 hours a week for me. Not a lot, but it's not nothing.