NO WAIT, OF COURSE THAT IS THE SINGLE MOST IMPORTANT SAAS METRIC

Summary from the TLDR Founders newsletter

There is no single most important SaaS metric - different metrics matter at different stages, industries, and circumstances of a company. Metrics like retention, top-line growth, net-profit growth, sales efficiency, LTV, Rule of 40, and NPS all provide valuable insights, but the key is to focus on the metric that aligns with your current goals and challenges. Rather than dogmatically focusing on only one, companies should adapt their focus based on what's most critical to their immediate success and long-term growth.