When building a startup, data can be comforting and trustworthy but also introduce uncertainty if not used correctly. Data is only one lens on your business, and humans deciding what to measure, how to measure, and why to measure can bring biases and judgment. It's essential to get on the same page early on regarding metrics and focus on data that's important to you, not necessarily what conventional wisdom tells you to measure. The world of startups is full of "golden rules" about dated metrics like bounce rate and pages per visit, but these offer information that isn't actionable and doesn't matter to your business. Instead, focus on fundamental metrics such as intent to use, activation, and engagement to understand the overall health of your product. When a VC comes knocking with questions about your business, you need to have your house in order, including knowing the difference between gross churn and net churn. Data can be a powerful tool for any startup, but relying solely on data can bring you to a local maximum rather than allowing you to hit your full potential; instead, iterate and optimize, and never take the steps required to get out of that local maximum.