Success in the military is described like this: A mission progresses by defining the tasks, obtaining the tools necessary to complete the task or tasks and then determining the metric for defining success. The metric, therefore, is attainable at one level and desirable at another.
Generals have used this model for centuries. All military officers strive for the desirable but often will denote success if the task is attained. We might think of the model this way: Something is better than nothing, but it is not quite everything.