The other day I posted about the swing between supply and demand. Today it is about the option of either centralizing or decentralizing purchasing. As you can see based on the image that once you pick a stance, then you tend to determine that your solution is the best.
Getting either method to work is seldom easy. I would rather believe in situational control. Often called the hybrid methodology.
In some circumstances you need to centralize so that you have control and can leverage the knowledge and skills of a group of people. Other times you have departments that can manage the process on their own and they don’t need an extra step to be added.
What works will depend on you and your organization. My advice is don’t be too rigid in keeping with what you have. Always be reviewing and checking with your clients to see if you are meeting their needs.