People tend to be overweight in recent experiences, and the positive or negative perception of one is disproportionately determined by the last episodes of the entire experience.
A vacation that starts bad but has a pleasant ending is likely to be remembered favourably; the opposite sequence may undermine the overall experience.
Likewise, the last 20 minutes of the movie determine the genre for the general audience. This effect is often achieved in Indian cinema by having a comedian or everyone cracking jokes at the end.