By now I'm only part way through White Night, so obviously I can't exactly talk about what Harry's doing in the latest books. But this one is already proving me right. Though in a surprising way.
Why oh why didn't I also guess that Harry would get an apprentice? Every great wizard needs an apprentice. And I've been told plenty of times before (including by my Ph.D. dad who used to be a professor) that there's no better way to learn than by teaching. So it would only make sense for Harry to grow in his own power by teaching someone else.
And now, a relevant paragraph proving that Harry has grown:
"If there hadn't been a war on, and if I hadn't been spending so much time drilling Molly in the fundamentals -- and therefore getting in all kinds of extra practice myself -- I would never have considered attempting to create such a complex focus. It was far more complicated than almost anything I'd done before. Five years ago, it would have been beyond me completely. More to the point, five years ago, I wouldn't have been as experienced or as strongly motivated" (96).
Later, on pages 125-6, Harry tells the reader that teaching Molly is why he's gotten better. In teaching her meditation he's had to review the basics himself, and (perhaps because of his many years of experience) he understands them better now than when he was first taught them by his own teacher. "I'd been getting almost as much insight and new understanding of my knowledge from teaching Molly as she'd been learning from me" (126). He then finishes preparing himself for a spell in about 10 minutes, which in a previous book had taken about an hour (I think).
And now, even though it's totally not related but because I've got to stick this awesome quote somewhere, here is something from a previous Dresden Files book.
"Of all my foci, the staff was the most versatile. Meant simply to assist with the redirection of forces I could use to call wind, to bend steel bars, and to channel lightning. I had used my staff to erect barriers of force, disrupt hostile magics, and in a pinch to beat the bad guys about the head and shoulders."
The Dresden Files: Blood Rites
by Jim Butcher