When I took driver’s education as a teenager, we learned about something called “highway hypnosis.”
It happens when you stop paying attention to what’s going on around you and you just drive along watching the white lane markings mile after mile. You lose sight of the big picture and get hypnotized by the minutiae, which can cause you to miss important things like your exit or another car swerving into your lane.
In conversion optimization, you can experience a similar phenomenon. When the newness of your website has worn off, website hypnosis can set in. You can lose sight of your overall strategy, leading to crucial mistakes.