“Before I go more into UVs I will be showing various colouring techniques that will help explain why good UVs should be made for a model. UVs are only important if you are going to “port” your model to another 3D package, but they also come in handy when applying textures to the model.”
http://www.3dtotal.com/team/Tutorials_3/zbrush_training/lesson_08/zbrush_lesson_08.php