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.
In Architecture Without Architects, Bernard Rudofsky documented the ways in which most cities were mostly built by improvisation, following no consistent formal design. Building was added to building, street to street, their forms adapting to different site conditions in the process of extension.
Rudofsky thought that this hidden order is how most settlements of poor people develop and that the work of improvising street order attaches people to their communities, whereas 'renewal' projects, which may provide a cleaner street, pretty houses, and large shops, give the inhabitants no way to mark their presence on the space.