When explaining the need for iterations, or better, having potentially shipable product every month or less, I often explain this as done in the video.
I make a comparison between a u-boat and a
dolphin, and explain that software does not surface by itself. Software is intangible. That makes it so great and makes it possible to ship it to the other side of the world in a second, however, that also makes it intangible. You cannot inspect software if you do not ask for that. So, the main benefit of iterative working (as in Scrum) is that you install an inspection moment. You have the chance to see how things are going. That gives feedback and feedback makes you learn and move faster.
So, when you are involved in a project that is crucial to you and it deals with an intangible material, please make sure the team follows the dolphin route. That way you can inspect progress and control it towards a successful result.
And you don’t have to wait till the end. Every result is shipable, so there is value in each and every iteration. Why not use that value instead of waiting till the end?
More recently I am using the above picture to clarify that better. Every Sprint result is a present: a shipable product. When teams focus on really delivering working tested software, that makes you Agile. After all, you can always stop in the middle and move somewhere else. The available product is shipable and contains the highest available value.