Art is designed experience.
The next question is whose experience. 
The artist is the designer.  The artists experience of the product is inherently different.  The artist can and does adjust the work.  The work remains in progress as long as it is in the artist's control.
The artists experience is of flux.
Every creative solution is inherently unique.
Art happens at the encounter of the "viewer" and the work.
The artist can only try to make art.
The artist has no direct control over more than half the experience.