"We are what we repeatedly do. Excellence, then, is not an act but a habit."
- Aristotle
I don't believe excellence in photography (or any art) is something we can reach through some kind of progression. As I've argued before, we are only one click away from our best image ever.
Skills play a role in photography, but in my opinion it is minimal. Once you master your camera and have an idea of what you want to create, experience takes a back seat.
Experience could in fact be harmful: we play it safe and repeat what's worked well in the past. Better to be a beginner forever instead.
How, then, are we supposed to achieve excellence in photography?
By doing, of course. By getting out and making more and more images. We have to create a lot of bad ones before we achieve that excellence we are looking for. Then we'll have to create more mediocre ones if we want to excel again.
Excellence is born when the right circumstances get together: an artist with the will to be at the right location, the passion to be there under the right conditions, a vision in mind -even if still in the subconscious-, and the right amount of luck.
Most of these factors are out of our control, the only thing we can do to create good art is to simply do it.