Two great creators have offered the same base concept:
Pablo Picasso: "Inspiration exists, but it has to find you working." (taken from above)
Ralph Vaughan-Williams: "I work as a composer therefore I must keep office hours to compose" (my own favourite quote)
Both suggest that the art of creating is not random or happenstance or moments of serendipity but one of hard work and application to the task of creating new material. Embedded in both but not clearly stated is the idea of study and reflection on the practice of creating in your specific field.
Scott Adams via Dilbert offers what appears to be a contrary opinion: "Creativity is allowing yourself to make mistakes, Art is knowing which ones to keep!"
However, embedded in that longer quote is the concept that you are constantly creating and sifting your work for diamonds in the rough (one of my old bands
) - i.e. you are still working constantly to create and discover the great pieces of your work
None of the above means that you must work consistently, but it is through consistent work and persistent self-analysis that you will come to your creative voice; to think otherwise is succumbing to the similar misconception that "there are no rules it's music" - yes it is music but even music has acquired, through accretion, expectations of where certain phrases and chords should go to next - these are our shared communal ideals of what makes good music, however, I would contend that such expectations do not lead to great music as there are several alternatives for continuing melodic and chordal movement that take it from the mundane to the sublime