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 learned years ago how important it is to shoot the same subject and location over and over again.
The practice teaches a photographer how to form deeper relationships with the subject, and better understand how the primary subject interacts with secondary elements – like the way high tide may introduce a stunning new reflection, or how a blaze of stars in a dark sky might be the missing element that lifts the image to new heights.
Revisiting a subject also serves as valuable “practice.” You cannot develop your skills in anything without a healthy (or obsessive) amount of practice. It always surprises me to find out aspiring photographers think that they can simply photograph their two-week vacations once or twice a year and come home with compelling imagery! It doesn’t work that way.