You use your brain! This is how it was done before telemetry was possible. Good software was made back then. All our software today is built with or on top of

You use your brain! This is how it was done before telemetry was possible. Good software was made back then. All our software today is built with or on top of software that was developed without any telemetry. Today it's much more common to see companies / product managers using telemetry, instead of their brains, and making bad decisions as a result. There are always confounding factors, and they usually dominate. Collecting numbers is easy, collecting the right numbers is hard, product teams don't have time for that. Telemetry ends up mostly being used for excuses for bad decisions.