I realized my scope blog did not include much content because I clearly have no simple solution because it is not a simple problem. see Scope Creep and Other horrors
In my cottage example of adding a bathroom that turned into a new wing, I would like to explore possible solutions as a metaphor for any scope issue. The first thing is that the guy managing scope should have responsibility for the budget as well. That is why the project did not get off the ground.
However if somebody had come up with a design or concept that would have added a bathroom as the first phase of a larger addition the project may have gotten of the ground.
Again if I had really wanted an additional bathroom I would have pushed it harder. Being the sponsor, I could have insisted that the other members of the team come up with designs that met my requirements and did not blow the budget out of the water.
The key with the project was that the sponsor also was also responsible for the budget. Everybody else were conumers of the product. Imagine if the scope and budget responsibilities were separate unless the CEO got involved. I predict chaos and a fiasco. (Remember the project, Graham)
Project X's Rapid Results approach makes real sense. The challenge is designing the projects.