How did this exercise help you build empathy with prospective users?

Initially reading the one very detailed interview I did not really empathise with the interviewee, he seemed very lazy and continually contradicted himself. however, reading it through again when I was writing out post its all the most interesting insights were buried in a very detailed story, and in those detailed stories there were very consistent pains, needs, and desires.  It helped with empathy because it removes all the “noise” from interviews.

How did the clustering of information help you to understand user needs?

Clustering helped to identify and visually represent which needs were common across users and which were outlying data points.

What was difficult or challenging with the technique? how would you do it better next time? 

I wasn’t writing enough my cards and had little to no context. Next time I would write them as more detailed I was also repeating points on cards (I think next time if there is a reoccurring statement I will put an ‘*’ next to it to remind me that it was important)