A schedule is just a schedule

StickyMinds.com : The Meaning of "Schedule"

A real schedule is hard to predict, and puts a focus on accuracy that some of us don't want to see ahead of time. In our high-stress community, sometimes we expect rewards for busyness and speed, not for accomplishment and quality. People want to believe that longer hours mean more work gets done, whether this is true or not. Managers want to believe that a pushed project finishes faster, whether this is true or not. Studies have cast doubt on both these notions, but the notions live. We're not quite ready yet to give them up.

The article describes a variety of potential hidden meanings behind a schedule and then gives the above advice about a schedule that is simply a schedule. Everyone recognizes that the schedule cannot be carved in stone - it is drawn in the sand and sometimes there is high tide that makes us completely redraw the schedule.

Another excellent find from Frank Patrick in his discussion of Late Projects and PMO's. Frank reminds that explicit acknowledgement of uncertainty in the schedule helps build shared understanding of the health of the overall project.

And this is the heart of Critical Chain Project Management.