The wild part, for me at the time, was how many steps there were from cause and effect and how perfectly they'd been reasoned through. The first time I had that experience was my first real "this LLM stuff might have some legs". My second similar experience several days later was "hmmm that wasn't a fluke..."

I'm still at a stage where I'm not completely sure that I like the code that Codex or Claude wants to write. Sometimes it's good, sometimes it takes 5 or 6 iterations to get it somewhere I'm happy with. But wow, on the front end of the work, they are great design/review/iterate partners; sometimes I let the tools write the first draft and then I find the gaps, sometimes I write the first draft and let the tools find the gaps. Either way has worked really well for making solid debt-free progress.