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.
There are two classes of problems caused by new technology. Class 1 problems are due to it not working perfectly. Class 2 problems are due to it working perfectly.
...Class 1 problems arise early and they are easy to imagine. Usually market forces will solve them. You could say, most Class 1 problems are solved along the way as they rush to become Class 2 problems. Class 2 problems are much harder to solve because they require more than just the invisible hand of the market to overcome them.
...Class 1 problems are caused by technology that is not perfect, and are solved by the marketplace. Class 2 problems are caused by technology that is perfect, and must be solved by extra-market forces such as cultural norms, regulation, and social imagination.