The value of iterative delivery is that it allows you to inspect often.
I'm sure you're all experienced the problem when someone tells you they're done and then you find out later that they were "mostly done - like 80%".
We all know how long that last 20% takes.
So this introduces two important concepts: The definition of done, and not believing it until you see it.
When someone tells you the requirements are "Ready" you'll want to review that before throwing it into the backlog and bogging down a team.
Similarly, If demonstrating everything at the end of a iteration is too onerous - then demo as you go.
Whatever you do - make sure the project sponsors and stakeholders see it occasionally as well. This transparency helps avoid other issues.
