To really understand what you are doing, you need to have metrics on the user behaviors.
Metrics should be the only way for you to make decisions. That's how you'll know if a feature is worth pushing, if your acquisition channel work, what the cost of a new user is, etc…
<aside> ⚠️ There is a whole controversy about tracking users. Most of the analytics tools don't really respect customers' privacy. But it's not a fatality.
Some tools like Fathom or Plausible(made by indiehackers) are super respectful. Use them if you don't need super-deep behavior analytics!
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How to Set KPIs and Goals (SUS 2019) : YC Startup Library | Y Combinator