I was up extremely late last night writing a project-status email. I could tell my paragraphs were not tight. I told Cursor: rewrite this 15% smaller. I didn't use the output verbatim, but it gave me several perfect rewrite ideas and the result was a crisp email.
I have it summarize my sloppy notes after interviewing someone, into full sentences. I double-check it for completeness and correctness, of course. But it saves me an hour of sweating the language.
I used it to get a better explanation to a polynomial problem with my child.
I use it to generate Google Spreadsheet formulas that I would never want to spend time figuring out on my own ("give me a formula that extracts the leading number from each cell, and treats blank cells as zero").
Part of the magic is finding a new use case that shaves another hour here and there.