Improving User Retention, applying "Hooked" framework 📈

I read the book "Hooked" by Nir Eyal over the past weekend, which very nicely breaks down why users users come back & get continuous value from certain products. My main learnings as someone who is struggling with getting good retention metrics: 🏹 Trigger: Don't just hope users will remember your product. You need to get people to open your site multiple times until your real value is apparent. Classical examples are required sign-ups, newsletters, mobile app installs. The most powerful form of triggers are internal feelings or thoughts people associate with your product - e.g. boredom, social validation for Twitter. This is the reason you open these apps when in the bathroom 👀 🏃 Action: Your product must be the simplest solution to an actual problem users have. It should be incredibly easy to get what someone opened your app for. Google is the ideal example, it's so streamlined that you'll type in your question before really thinking about it. It's even in your browser bar and listens to your voice! 🏆 Variable Reward: However, predictable results are boring - imagine how rarely you'd use YouTube if it only gave you videos about that specific product, place or person you searched for. Present people unexpected but useful information in addition to their original intent. Social networks excel at this, another example is how shows TV shows become boring in the 3rd season - even though the content objectively stays the same. 💰 Investment: Lastly, make the user do a bit of work to improve their next visit - but only after they've gotten value. Natural examples here are recommender systems like rating movies on Netflix after you've watched them. But no-one wants to add every film they ever enjoyed up front! If done right, this step will make users feel "invested" in your product unconsciously - inertia against loosing progress. LinkedIn nudges you to add largely irrelevant information to your profile, because you won't abandon all descriptions and contacts you added to it. 🤝 Any other tips? There's tons of great content in the book, plus it's only 215 pages. Highly recommend it! Any other examples, or something you recently learned about user retention?