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.
Ugh, now I have to write this boring part, I would think. I would spend a few days in active rebellion against this directive that I imagined the book was imposing.
Then I would realize: this is my book! There are no rules! I can write it however I want! Also, I would think, if I’m bored by something that I believe I need to write, the reader undoubtedly will be too, if not because the subject is inherently boring, then because I myself find it so unbearably tedious to imagine discussing it for five pages. Often as not, I would remember some aspect of the subject that deeply interested me, something a little outside the way it’s usually perceived or written about. Then I would meditate on that, and soon I would be scribbling notes from an increasingly excited place until I found a way forward. A form of beginner’s mind.