The below 2 minute video of Ira Glass explaining how the secret to artistic quality is to do a lot of art is well worth your time.
Bayles and Orland make the same point in their terrific book Art & Fear. They tell a (true, I believe) story of two pottery classes:
In the end, it was the students who created many pots who also tended to create the best ones. This is for at least three reasons: