Anthony Tjan suggests the three-minute rule:
While there are obvious ways to gain significant customer understanding, such as surveys and focus groups, some of the most interesting insights come from less direct analyses. Take our three-minute rule as an example. You can learn a great deal about customers by studying the broader context in which they use your product or service. To do this, ask what your customer is doing three minutes immediately before and three minutes after he uses your product or service.
An example:
At Thomson, one of our products provided investment analysts with financial earnings data. What we hadn’t fully appreciated — until we applied the three-minute rule — was that immediately after getting our data, a large number of analysts were painstakingly importing it into Excel and reformatting it. This observation led us to prioritize developing a more seamless Excel plug-in feature with enhanced formatting capability over other product development initiatives. The result was an almost immediate and very significant uplift in sales.
(Hat tip to Kevin Meyer, who doesn’t normally like the Harvard Business Review.)