This is a post by Cat McClintock on PTC site.
You’ve designed your product exactly to the specifications you were given, and everything looks great. There is just one thing left to do–route the cabling harnesses.
As you start working on it, you discover that there really is only one best way to route everything, and it’s not optimal. You send your design off for prototyping, and when it comes back you find out that your cable routing isn’t going to work. What can you do but start all over from the beginning?