Lately, I had to explain the Scrum methodology used in software development. I created a little infography on this topic.
To ensure that no surprise arise at the beginning of the project, I secure it with an initial RUN-0 solely concentrated on architecture and infrastructure. This avoids multiple refactoring during the course of the project and the surprise of the product owner to have so few implemented feature at the early stage of the product.
Identically, the last RUN-final is secured so that no feature or request is taken into account. It's the project closing. Only bug fixing is allowed. This avoids any new feature that could risk the whole project delivery. This is one of the key to success and quality for Scrum projects. An other one is to take into account bug fixing during the RUN-N as high level priorities entries into the Sprint backlog.