Everyone has heard that practice makes perfect.
Practice, without aim, technique, or guidance does not result in perfection. Unless you practice it right, it's not going to suddenly appear perfect.
One of my ballet teachers, Mr. Adamson had a saying. "Practice does not make perfect. Practice makes permanent."
Picture from http://www.flickr.com/photos/peculiarmomma/1594538553/in/set-72157602462231066/ by Shalet Ann. Attribution, Noncommercial, Non-derivative License.