In my experience it can really only competently do the 80% that takes 20% of the effort. Brainstorming and planning and gathering data - and even that you have to sift through for accuracy so maybe it saves 10% of the work in the best situations.

The biggest benefit I've gotten from AI is that it sometimes enables me to do some things I never would have been able to do with a small budget and a small team. But that didn't save me any time, maybe even required more time.