The HelloWallet 2.0 Launch (2010)
Initial pre-launch user testing came back, overwhelmingly supporting a hunch that the designs we were using were not very friendly. Since this was our big release at Finovate (the biggest financial technology conference), we needed to test some other UI options. Oh, and you have 4 days until engineering needed a final direction.
What followed was 4 days of constant iteration and user testing of different possible directions for our initial rollout. We knew that we couldn't change. I was made Lead Designer only 3 weeks before, so we only wanted to iterate on components that were reusable.
At the time, 1 product manager and myself would run to local coffee shops and conduct a card sorting exercise that had them rank designs we gave them under various emotional characteristics. Eventually, we finally went with a blue variant (as is the majority of the explorations here), since it clearly gave users a helpful, positive impression.