One of the modes of the XP PlanningGame.
Isn't this just the bad old "we have now delivered what we wrote in the contract - five years ago... oh, you've changed your mind?" routine?
Only if you fix scope, then vary time extremely. The same can be true of FixTimeVaryScope: "Well, today's the last day of the program. As you can see, here's the splash screen - sorry about the rest of the functionality we couldn't deliver. Will you be cutting the check today or tomorrow?"