Do not confuse the images of reality with reality itself. ‘Ceci n’est pas une pipe’. Art is a world of its own created by the intuition and ideas of the artist. And this creative process never stops. The artist may be satisfied with a certain result reached at a certain moment….. (using his/her own judgement, since there is no fixed or agreed standard on how to make a work of art). So, somewhat later, his intuition and ideas are likely to change. He may feel unsatisfied, even feel that his work had failed. So he would like to redo, renew, change the work of art, partly or entirely. The work of art is never finished. People may think that they buy a finished product, but that is a misunderstanding.
Alberto Giacometti is an example of this never ending unrest, endlessly copying, never satisfied, only to discover how deeply conventions influence the way artists work.