Abandoning Best Practices in UX

When should one abandon best practices in user experience, and what does it take to declare that something is a best practice?

[csa]

My notes:
People don't intensively use websites. How might we test and get the best practices on seamless user experience? It is normal for people to learn and repeat the tasks before getting used to it, however it naturally works well on the major or enterprise platforms.

How about other business or platforms that has less traffic? Usability testing can be one of the ways to validate the user experience if the business uses unique approach and patterns. By saying that, we don't always do that because we already know some common patterns that works.