Eisenhower's quote Plans are worthless but planning is everything is the basis of an article in the Army Leader well worth reading, downloading, and keeping at you side at all time.
In our Federal Acquisition world, the Integrated Master Plan is the basis of program management success. The IMP tells us how the increasing maturity of the program's capabilities is progress, using Measures of Effectiveness and Measures of Performance.
Here is a set of resources on the topic of Integrated Master Plan / Integrated Master Schedule starting with What Does Done Look Like.
If we don't have an answer to that question in units of measure meaningful to the decision-makers, we're on a Death March project just as Edward Yourdon told us.