1) The cognitive burden is much lower when the AI can correctly do 90% of the work. Yes, the remaining 10% still takes effort, but your mind has more space for it.
2) For experts who have a clear mental model of the task requirements, it’s generally less effort to fix an almost-correct solution than to invent the entire thing from scratch. The “starting cost” in mental energy to go from a blank page/empty spreadsheet to something useful is significant. (I limit this to experts because I do think you have to have a strong mental framework you can immediately slot the AI output into, in order to be able to quickly spot errors.)
3) Even when the LLM gets it totally wrong, I’ve actually had experiences where a clearly flawed output was still a useful starting point, especially when I’m tired or busy. It nerd-snipes my brain from “I need another cup of coffee before I can even begin thinking about this” to “no you idiot, that’s not how it should be done at all, do this instead…”