I really don't think that the film has been completely planned in the strict (and too rigid sense), for this would also have taken away much of the emotional power from the film, as is the case with many too commercially calculated/that is, too strictly preplanned films from the USA. Nevertheless, the story always has to be thought out, but I really find it is an advantage of the film that many scenes are played in a very spontaneous manner (that in my opinion also is seen in the fun of the actors to play it). It's really the human and optimistic feeling of the film that counts.