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.
Can we do anything to increase creativity? There are training courses, and books, as well as “brainstorming sessions” which are supposed to do this. Taking the brainstorming sessions first, while they were very fashionable at one time, they have generally been found to be not much good when formally done, when a brainstorming session is carefully scheduled. But we all have had the experience of “tossing an idea around” with a friend, or a few friends (but not a large group, generally), from which insight, creativity, or whatever you care to call it, arises and we make progress.