What's one business decision that saved you months of frustration? (I will not promote)

This project is a crowdsourced collection where entrepreneurs and professionals share a single, high-impact business decision that eliminated months of wasted effort. It is for founders, operators, and anyone seeking practical, battle-tested shortcuts to avoid common pitfalls. The project is interesting because it distills complex experiences into actionable, counterintuitive insights that can save others significant time and frustration.