That's a very good question and I can't find any decent articles on the topic.
The best guys seem to throw 65-69% strikes. I'm sure there IS a point, like you suggest, where you're throwing too many. You want, in some counts, for guys to chase balls out of the zone. And you want to keep them guessing. So yeah I'm sure something crazy like 90% strikes would be way too many and would probably make you too hittable.