I'm not so sure. Jobs learned at lot at NeXT, I think the next company/product he would have worked on would have gotten it right, even if it hadn't been Apple.
There is a very clear through-line connecting all the Jobsian products: an aggressively streamlined approach to features, a fascination with high-quality materials and novel industrial processes, and an aesthetic sensibility derived from Bauhaus/Functionalism/Dieter Rams. All these elements are just as present in his misses (Lisa, the original Mac, the NeXT Cube, the G4 Cube) as in his hits (iMac, iPod, iPhone).
What separates his age of mostly misses from his age of mostly hits isn't any change in his design philosophy; it's the passage of time. His misses mostly came early, his hits late.
What this implies to me is that his later success wasn't due to him changing, so much as the world changing around him. In 1984 and 1990 and 1995, he was trying to sell objects d'art into a computing market that was dominated by business/enterprise purchasers, who didn't care if the machines they bought were ugly as sin as long as they were functional and interoperable and cheap. By 2005 the market for tech had shifted away from those buyers into the consumer market, where the priorities were completely different, more like those of the fashion business than of the tech business of old.
Suddenly the Jobsian approach stopped being a liability and started being an asset. But that's not because he learned how to aim better, it's because the targets moved so that they were all neatly lined up in front of him.