The sooner you complete a usability study, the higher its impact on the design process. Slower methods should be deferred to an annual usability checkup.
The consulting business has an old saying: “Fast, cheap, and good — pick any two.” The notion is that if you want something done quickly and inexpensively, it’ll be of poor quality; if you want it quickly and done well, it’ll be expensive, and so on. Although true in many areas, this maxim doesn’t hold for one important aspect of usability: methodology.
In usability, the fastest and cheapest methods are often the best.
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