I had to write a simple desktop app for internal use. Nothing super complicated, but it did require some low-level system stuff that I have zero experience with. Had Codex code up something that worked perfectly. In total, spent a couple days making sure everything did work as expected and nothing stupid was going on. Would've taken me at least a week to research the stuff I didn't know, get a decent UI in place, validation, etc.
Submitted for code review and of course someone got bent out of shape because the agent used Array instead of List...