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.
I walked around with a map, penciling in X’s wherever there was a barn or shed. For the next three days, I covered four kilometers in all four directions. Living toward the outskirts of town, there are still a good many farmers in the vicinity. So it came to a considerable number of barns—sixteen altogether.
I carefully checked the condition of each of these, and from the sixteen I eliminated all those where there were houses in the immediate proximity or greenhouses alongside. I also eliminated those in which there were farm implements or chemicals or signs that they were still in active use. I didn’t imagine he’d want to burn tools or fertilizer. That left five barns.