The CFD, one of the most insightful, yet alienating agile charts out there. Unless you have a degree in mathematics most people find this chart to be fairly superficial, and to an extent you'd be correct.
Flow-based conversations are often very factual and data-driven, and the key to yielding value from CFD analysis goes beyond crunching the numbers and observing the peaks and troughs of each status.
Equally as, if not more important than the numbers are the stories behind them. What is the context that might have led to a blowout in the number of work items that were In Progress? Does it warrant a deep-dive discussion, similar to a retrospecitve? CFDs can be powerful tools for aligning conversations and identifying antipatterns, provided you use them correctly.