Platforms favor watch time because it is hard to fake and maps directly to their business: minutes watched are minutes of ad inventory. A 10-minute video watched halfway contributes more than a 1-minute video watched fully, which shapes the longform meta — chaptered structures, open loops, and series designed to accumulate session minutes.
In shortform, the equivalent currencies are completion rate and rewatches — finishing a 30-second video, or looping it, is the strongest signal TikTok-style feeds read. Watch time also compounds: videos that hold viewers lead the algorithm to test them on larger audiences, and binge sessions across your catalog teach the system to recommend your channel as a whole, not just single videos.
