Why use X-Scale? Depending on the manufacturer, many 3D and Inkjet printers contain very slight inaccuracies compared between the X (horizontal) and Y (vertical) directions. Over a large design area these inaccuracies can become noticeable and effect the overall quality of the final product. Adjusting the X-Scale to compensate for these slight inaccuracies can resolve the problem.
Other factors may also require using X-Scaling such as different materials chosen for either drops and/or substrate, various temperature exposure, etc.