Creator Insider dropped a long one with Todd Beaupré (senior director of growth & discovery). I made a video on it, but here's the short version for anyone who doesn't want to sit through it:
1. It's pull, not push. Nothing happens when you publish. The system fires when a viewer opens the app - it looks at who they are, what they've watched, what device, what time etc. **very personalised**
2. Stop unchecking ''notify-subscribers'' even if you change your niche - Your subscribers don't decide for everyone. The system can learn a video is flopping with your subs and working with people who've never seen your channel, and act on both separately.
3. There's no "most important metric" anymore. On a TV, watch time might carry more signal. On mobile, a like might. So anyone selling you THE number is selling you snake oil.
4. The sidebar stopped being related-videos years ago - it's personalized to the viewer. The #1 place people watch videos from channels they subscribe to is the suggested list on someone else's video. Not the subs feed.
5. ~90% of your subs skip any given upload. Even people who subscribed and deliberately opened their subs feed. That's the normal baseline. The system is built assuming most of your audience passes and goes hunting for the slice that won't.