Learned something yesterday. Couldn't believe how stupid Claude had become, as I've been writing about here, and then I noticed that I was using Opus 5 and not Fable 5. So I switched back and all of a sudden Claude is smart again. So I conclude that there's a very substantial difference between the two. It's overnight jobs were done more carefully and the report it produced is literate, understandable, and tracks what we had agreed to.