At the 2013 Goshen Rally, Lippert was checking front-to-rear axle alignment and recommending Correct Track II installation where the axles were out of alignment. Lippert's explanation is that it comes down to weight distribution. After you load up all the pots and pans, slow cookers, blenders, dishware, and fill the frig and pantry full of all kinds of goodies, and store your smoker, and that case of wine or beer, there's a lot of weight on one side of the trailer. The suspension compresses differently on the heavy side, and the axle spacing is different on that side.
So while alignment might be fine as the trailer leaves the factory, after you load it up, alignment may change. For the trailers that come with Correct Track I from the factory, Lippert recommends getting a Correct Track alignment check with the RV loaded the way you plan to travel.
While I was waiting to get our rig checked, there was a guy in front of me who found out his axles were off by almost an inch, causing serious tire wear. Our axles were within 1/8" which confirmed an earlier measurement taken at Camping World.