This is not my experience any longer. With properly set feedback loop and frameworks documentation it does not seem to matter much if they are working with completely novel stuff or not. Of course, when that is not available they hallucinate, but who anymore does that even? Anyone can see that LLMs are just glorified auto-complete machines, so you really have to put a lot of work in the enviroment they operate and quick feedback loops. (Just like with 90% of developers made of flesh...)