My videos are mini-documentaries about mystery and horror, in Spanish, and about 10 minutes in length (on average). My overall retention is 53%, for an overall views of 173K at this very moment. The channel is 6 months old.
My opinions and conclusions about the matter after this time on YouTube about this issue are:
- Small channels tend to have a very unstable retention rate, so neither praise nor discourage yourself: keep going and try to focus more on quality content and less on retention rates/optimization the first months. Do what you really like and do your best. Within the time, when you become more known for releasing quality content, more people will expect to find nice videos on your channel and will pay more attention for a longer time.
- Judging retention time has to be done upon several tens of thousands of views, not just a couple of thousands.
- Shorter videos always have a higher retention (it is logical), so a channel with a 60%+ retention rate but videos with an average length of less than 2 min. is, in my opinion, something neither good nor bad, just average.
- Longer videos always have a lower retention (it is also logical), and thus a channel with a 40-50%+ retention rate but videos with an average length of more than 6-7 min. is also quite average.
- The longer the videos, the more extraordinary will be to have a retention higher than 50%. It means that your content is appealing to a broad audience during long periods of time. That means, thus, that your content is not only good, but people want to watch the whole thing = you keep them watching.
Overall, I think it is more a matter of serving an appealing content. Also, I think shocking beginnings do play a role, but think about this: if your best punch is within the 5 seconds and then your performance gets worse within the seconds, retention is going to be low. Otherwise, if you go in crescendo with the surprises and the good punches, not only you will shock, but also retain people for the future. And this last thing is very important, because I would separate this phenomenon into 2 categories:
1) The short run: your videos are shocking at the beginning but then they decline. People will notice this pattern in your videos. They will know that after the first 30 seconds everything is going to go downhill. They just quit the video.
2) The long run: your videos are increasingly shocking and trapping (in the sense that they have no choice but to want to know more). People will notice this pattern and they will know that your videos only get better within the seconds or minutes. They want to know more, they want to know the whole story. They stay until the end.
So I think this is not just about considering audience as machines, but as human beings like you and me. Think in terms of what you behave like when "consuming" other's material. How do you act? It is about building your own name, a reputation, someone who will be identified as "a good creator of content", and therefore expected to deliver good material.
Makes sense?