One of the issues that all project managers face is the need to justify the costs that our projects accrue as they moves through their various phases. In many traditional waterfall projects benefits are only realized when the project reaches the deployment stage. By which time the project sponsors eagerness for the product or function may have waned.
Costs are regularly tabulated and criticized whilst benefits become a mythical land of milk and honey. Like the old western wagon train plodding across the Great American plains the heat and flies are there every day whilst the vision of California or Oregon is a misty and far off apparition. Like the cool mountains that shimmer in the far distance.
Agile and lean development methods attempt to address this issue by seeking to deliver function and benefits in small but regular doses. Even if the full deployment comes no sooner than with waterfall at least the sponsor can point to demonstrable function that they can sell to their bosses and peers within the organization.
We tend to forget that our sponsors are themselves under scrutiny and also have to justify their decisions and compete for resources. So "a little and often" is a motto that all project managers should bear in mind when considering benefits.