On the other hand, she might be so thoroughly traumatized by her experience at the hands of Justin and so driven to make certain she is never a victim again that she adheres to a fanatic regimen of study and self-improvement. A bit like the medical student whose close friend died of cancer who studies fanatically to enter into med school and/or to work as a research scientist. Highly motivated.
Elaine may also be motivated by a sense of competition with Harry. She definitely still seems to be influenced by him and his life choices, enough that she imitates him professionally. Like him, she's in the phone book, under "Wizards," and she's the same mix of wizard and P.I. She seems to take the same kinds of cases he would take, and help people like he would. Whether it's subconscious or not, I think maybe she's trying to emulate Harry a little. That kind of emulation could carry over into a sense of competition, and she did get a chance to see that Harry's skill was improving over time.
That said, though, Harry may have an advantage in increasing his skills that Elaine doesn't have: Harry has been teaching Molly for years now. He attributes much of his increased skill to having to teach her, and it's easy to see that in the later books. His improved skill with veils, for instance, came from the fact that Molly is so good with them, and Harry felt like he needed to be passably good with them himself just to be able to keep teaching her about them. Not to mention other things that he's said about the teaching process, about how teaching someone else the basics has made him go over them again himself, appreciating and understanding them on a deeper level than he did before.
And aside from teaching Molly, he's also been teaching Warden recruits over the years. Just being placed in a position of instructor has forced him to develop his skills to the level of an instructor. I'd guess that this has moved his skill level quite a bit beyond where someone of his age would normally be. I know he still thinks of himself as a magical thug, but the reality is probably more that he's far more skillful than wizards of his age would usually be.
And that was before he got the Winter Knight mantle. He seemed to be throwing around an awful lot of cold-based magic, pretty much as soon as he took the job. His thoughts seemed to run in that direction without him even having to work at it. Who knows what that could indicate about his skills with that sort of magic now? Whereas before he would instinctively use fire, now he seems to instinctively use cold magic, while still retaining his abilities with fire.
