There is no one-size-fits-all definition of how product market feels, but we tend to think about it as physics resonant frequency: When an oscillating force is applied at a resonant frequency of a dynamical system, the system will oscillate at a higher amplitude than when the same force is applied at other, non-resonant frequencies (wikipedia.org link) – you are not exactly sure where it is (because real-life systems are often too complex to have exact systems), but you can measure it and identify when you are going in the right direction, and once you are in the ballpark, even if not exactly spot on, the system will amplify its own signal.
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Cover art by: https://groco.com/uncategorized/how-to-efficiently-scale-with-capital/
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