Feature Estimation
There have been countless times when a customer has described some new software functionality they want and are dumbfounded when I can’t give them a ball park estimate without a ton of if’s and but’s. When you start breaking down the functionality and everything that naturally flows on from that new functionality does the customer realize how huge a task can get without explicitly acknowledging many constraints up front. Check out “The fractal nature of UI design problems” for a great example of how functionality requirements are deceptive in their apparent simplicity.