An hour is all the time that is necessary to relay all of the pertinent information, and it increases the amout of reader involvement, suspense, and interest. Also, if we had a lot of time to hear the entire story, to understand fully how Louise felt about her marriage, then the ending would not be as powerful as it was. Instead, Chopin allows us to feel sorry for Louise as she weeps at the news of her husband's death; if we had been with Louise for a long time, we would know better, and not feel the same dramatic shock at a woman hearing the news of her husband's death. We are to suppose that it was devastating. The fact that we feel this way makes Louise's succeeding emotions of freedom and exhilaration even more unexpected, interesting and unusual. We are left wondering and questioning why she would be so happy; it seems awful! That piques our interest and makes the story more suspenseful. If we had known more about the characters because it was set in a longer time-frame, her happiness at his death would have been no surprise, and so the story would have lost its suspense and interest level. Instead, we have to use our heads to infer what their relationship was like, based on tiny clues that Chopin gives. For example, Louise had a face "whose lines bespoke repression," and
"There would be no powerful will bending hers in that blind persistence with which men and women believe they have a right to impose a private will upon a fellow-creature,"
and, "yet she had loved him, somtimes." With these small clues we are left to fill in the details; that makes the reader more involved, more likely to insert their own emotions and beliefs into the story. This enables a personal connection with the story. Then, the ending's irony is more potent as the doctor miscalculates that she had died of "a joy that kills." We feel we know better, we feel smart for having figured it out instead of it being handed to us on a plate, and her death is even more shocking because we knew her only briefly before she died.