Above 50% average view duration is considered good. Above 70% is excellent. YouTube promotes videos with high retention in search and suggested.
The biggest drop-off points are: the first 30 seconds (hook failure), after the main point is made (mid-video), and before the CTA (end screen avoidance).
Pattern interrupts reset viewer attention by changing the visual, topic, or pace. Without them, attention naturally drifts every 60–90 seconds.