O'Reilly logo
  • Aaron Wolfson thinks this is interesting:

One of the most important ideas behind Lean UX is that we don’t assume that a new design or feature is automatically better than what came before it. We test everything. When we ship a new feature, we test to see if it made a significant impact on important user behaviors. When we change text or the timing of an email, we test to see which version performs better. When we make a change to a user flow or a navigational structure, we make sure we haven’t inadvertently made things worse for users.

From

Cover of UX for Lean Startups

Note

It's kind of presumptuous to do things any other way, no?