Cons and caveats of usability inspection

At first glance, usability inspection seems like a perfect tool to test designs. It's cheap, fast, and can be done at any stage of a product lifecycle. However, there are some downsides:

• Usability inspection methods are based on theoretical principles. They can't replace an actual user interview or observation of users performing tasks in your app. Ideally, inspection should be followed by user testing.
• An evaluator is a human being, and they have their own biases.
• While heuristics and usability principles are universal they can become outdated over time. A better strategy is to create heuristics tailored to your product and brand.