If I can't write the final beat of a story, brief, or article, or the last five seconds of a commercial or video, I know that the premise is not yet fully realized. Those concluding seconds, or those cascading syllables leading to a final conclusive sustaining note should resonate. The end should resolve, summarize and underscore the point. If those qualities are absent or not sufficiently present, then the foundational work - the premise in most instances - is not done; the ad, video, short story, screenplay or novel is not complete. The piece might move, twitch, even walk, but it won't fly.