I'm writing an article on marketing data discrepancies specifically for enterprise and large marketing teams. Write about one or all of the following questions: 1. What is the single most common cause of data discrepancies across marketing channels, and what is the first thing you do to fix it? 2. What is one rule your team enforces that has had the biggest impact on marketing data accuracy? 3. When you discover a discrepancy between your ad platform data and your analytics tool, what is your diagnostic process? 4. How do you maintain data consistency when external agencies are involved? 5. What is the one governance practice that prevents most data discrepancies before they happen?