For most patterns there isn't any, but when you have a pattern that has a whole lot of color changes in a very small area (this pattern had a section where every stitch in a 10 stitch wide row was a different color), it means not having to constantly tie off and rethread needles. It also means you won't run out of places to secure your thread ends, which is what happened to me on a previous pattern and why I decided to try stitch parking. But like I said, I don't use it for everything. If a pattern has nicely sized blocks of color, there's no point.