[adrianhoward]

Even better - have A/B testing and experts. They're good at understanding why some A/B tests come out certain ways, can point out issues that might need further investigation, and can help discover new tweaks and fixes that you can, in turn, A/B test.

(I know Patrick isn't saying this - but I hit the 'we don't need UX / we don't need usability tests - we A/B test!' thing quite a bit now and it's bloody annoying. Both because (a) yes you do, and (b) the folk saying it are usually doing a lousy job of A/B testing ;-)