Once you see that an answer is not serving its question properly anymore, it should be tossed away. It's just their natural life cycle.
They usually kick and scream, raising one hell of a ruckus when we ask them to leave. Especially when they have been with us for a long time.
You see, too many actions have been based on those answers. Too much work and energy invested on them. They feel so important, so full of themselves. They will answer to no one. Not even to their initial question!
The hardest thing about customer interviews is knowing where to dig. An effective interview is more like a friendly interrogation. We don’t want to learn what customers think about the product, or what they like or dislike — we want to know what happened and how they chose... To get those answers we can’t just ask surface questions, we have to keep digging back behind the answers to find out what really happened.
Now, I understand deadlines. I understand that the plane will take off whether or not I’m on it, or the importance of beating the holiday retail rush, or that "the show must go on". It is perfectly clear to me how people use timekeeping technology to coordinate social activity. It’s actually quite remarkable when you step back and look at it. But, over the years, I have observed that there is a difference between those examples and the ones around the delivery of Things, which tend to be completely arbitrary. When you wrap an arbitrarily complex endeavor up in a neat launch date, the goal seems to be more about coercing the people beneath you to absorb the overhead of all the details you left out—that or sweating it yourself. As a tool for coordinating human activity, I have come to believe that the Thing-deadline calculus is, considering more sophisticated alternatives, unnecessarily crude.