A plein air study is very different from working on a painting on consecutive days.  I do both.  In the case of the two paintings done recently in Giverny from my hotel Le Calendal.  Because I was also teaching and helping the participants I did not actually have extra time to work on these two paintings.  Upon inspection of the works I am really glad that I didn't have any more time because they feel very fresh and unlabored.  I will take these two paintings and make two more that will incorporate a little more information and refinement but I will keep the "freshness of the mark and spontaneous response" that I think are evident in these two pieces.