His tenure was hugely successful, especially at the beginning. Apple was in lots of trouble, Mac sales way missed forecast, and Sculley turned the entire company around after firing Jobs and Apple was very profitable for most of his tenure.

Sculley wasn't good at finding the next great thing, so he's a perfect example for most startups. Once the founders figure out what their real business is, the key is execution. If the founders can't do it, bring in someone experienced to do it.