The Simplest Model

I think I may have finally figured out the simplest possible model for PPM:

 

All projects follow a flow that works something like this model.  Someone decides they need something.  The Need either gets approved and becomes a project or it does not get approved and it sits on the Need stack.  If it gets approved, then a project gets Executed.  Sounds simple, right?

Unfortunately, things start to get a bit more complex.  A few quick questions:

• How do we define the need?
• What are the criteria for approval?
• How do we know if it's a good idea?
• Who will approve it?
• Do we have the resources to do it?
• What will we choose not to do as a result?
• If we decide to do it, who will do it?
• What conflicts will happen as a result?
• Who will get overloaded?
• How do we monitor progress?
• Who is responsible for realization?
• How do we know if we hit the target?
• What happens if the goals change mid stream?

I could go on.  You get the picture.  But at least this is a starting point for agreement.  From here, we need to go a bit deeper into where this model begins to fall apart and why