This happens all the time to me. The model emits thousands of lines of high-quality code, making vast progress very quickly, but on the way does a few very, very stupid things a human being would never have been silly enough to do.

Then it takes hours or days - sometimes weeks - to find and fix the AI-induced problems. If you very, very tightly constrain the AI by using structured processes and unit tests you can work wonders with it, but you do start to wonder to what extent this is better than if you had simply coded it yourself.