Every time I shoot, it's kind of like (in some ways) I'm practicing for the next time I shoot. Every time I write, it's like I'm practicing for the next time I write. Practice and repetition are the things that advance or have advanced my skills like nothing else. Better than new gear, learning new techniques, better than anything else. The more you do something, the better you get at doing it. (Theoretically, at least.) While this may sound overly obvious to many of you, I still think it bears repeating for those who somehow expect their photography to be akin to instant pudding in terms of development.
In pro baseball, the best sluggers still do batting practice. Pro basketball players still repeatedly practice shooting hoops. If you're a golfer, there's always value in spending time on a driving range no matter how good a golfer you are or how low your handicap happens to be.
The same holds true for photography. Practice and repetition are the keys to better photography. Practice and repetition keeps you on your game. The more you shoot, the better you get. The better you get, the more you shoot. It's a never-ending loop that benefits all who are caught in the loop. Getting caught in the loop, of course, is a good thing. A very good thing! (Assuming you're interested in becoming a better photographer)
People who watch me shoot glamour models sometimes say things like, "You make it looks so easy." Well, that's because I've done it so many times and every time I've shot, the act of doing so became (in some ways) another practice exercise. In other words, the more pretty girls I've shot, the more practiced at shooting pretty girls I became. Take me out to a ball game, for instance, with a front-row field-level seat and have me shoot the game and you'll see how difficult I would make that look. That's because I've never shot a baseball game from a front-row field-level seat, much less spent any time practicing it.
By the way, there's a difference between practicing and experimenting. While experimenting is important to a photographers' growth and development, it involves doing things in new ways or shooting different sorts of things than what you're most practiced at doing. When you experiment, you're not practicing what you already know how to do. You might be exercising some of what you already know while applying those skills to something different, but that's not practice. If every time you shoot it's an experiment, a new experiment, you'll never get good at it even if you were lucky enough to snap an awesome pic or two during your experiment. Being good at something means you can do it, whatever "it" is, repeatedly and consistently and with the the same or similar results. Practicing what you already know to do will likely do more for your overall skills and abilities than constantly engaging in experimentation.
Can too much practice make you too good? Photographer, please. In photography, as with many other endeavors, there's no such thing as being "too good," I don't care who you are or what you've already accomplished. You might be good, but you'll never be too good.
The pretty girl at the top is Aurora. I snapped it about 5 years ago. While it's said a picture can tell a thousand words, sometimes it only takes two words to explain a picture.