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.
Specialized tools like bench shears have proliferated throughout history in part because craftsmen necessarily do the same task with the same tool over and over. After a while, the task becomes routine, and the craftsman is able to perform it with predictable skill. The most creative of artisans is frequently one who, in the midst of routine, pays attention to the details of the work and the tools that effect that work, and so it is that the reflective craftsman develops ideas for new and improved tools in the course of working with those that he perceives to limit his achievement or efficiency.