You're absolutely right. FWIW, I think this iterative process should take place before publishing your API. Sometimes a design needs to 'sit' for a month or two

You're absolutely right. FWIW, I think this iterative process should take place before publishing your API. Sometimes a design needs to 'sit' for a month or two and be used a bit before you realize its boundaries: what it does well, and what could be improved. If you're judicious about improvements (i.e. don't rewrite) you'll avoid the second-system effect and put out an API that'll be better than your first attempt. I realize that's not always possible.