I have long been a proponent of making sure that someone less familiar with a feature take the lead on testing it immediately before release. My general reasoning was that a new set of eyes will notice the issues that everyone else has accepted.

Jono Bacon in his book The Art of Community has a a great description of this phenomena in a sidebar on page 123 entitled “The Risks of Autopilot”

A common problem that can occur when observing how people use software is when the user knows of a particular quirk in a product and works to naturally avoid triggering the quirk. This is common with software developers, and before release, the software typically is not used in the same manner as it is by normal users after release.

Thanks Jono for such a great description of this issue.