Waldemar,
Blueprints are simply contracts that are used to punish users for giving their honest opinion about how real software fits their real world. I believe the only time a business really understands whether a configuration will work in their environment is when they try to use it. You can't "use" blueprints. They are only a representation of the solution.
I believe the Realization phase should be looked at as the time when the Blueprint gets updated to reflect reality. It shouldn't be thought of as the period where the Blueprint is implemented.
The challenge is how do you spend the minimum amount of time and energy to get to the point where real users have something real to evaluate? A related challenge is how do you "contain" the number and types of changes that you allow those users to make to the system? Those are the real project management challenges.
Sam