While it's true that data tends to decay over time, you always need to be sure that you are analyzing the right data. As marketers, while we become more and more inclined to a data-driven approach to enable customer experience, the key question to know is "Are we even looking at the right data?" (Or) "Do we have access to the right data?" Put yourself in the shoes of the customer and you'll realize that most times, great CX need not always be about wowing the customer at every opportunity.