Remember a few months ago we mentioned Tuckman's 5 stages of team development? Sure you do; forming, storming, norming, performing and adjourning.
Well, here is another view which I think is pretty interesting. It's called Punctuated Equilibrium. (The name is borrowed from evolution theory.)
The basic idea is that about midway through any project type activity the people working on it will see the deadline is suddenly a lot closer and will naturally elevate their productivity.
You can read more on this topic here.
And while we are comparing models, have a look at this one, which overlays the Tuckman's five stages with Gersick's PE models.
The implication for project managers is that a series of smaller, but significant milestones enables project teams to maintain a more elevated performance level over the course of the project than if they are just aiming for the big delivery day at the end of the project.
It's scientific proof of why iterative developments are more effective that one big-bang release.