Project Plan is a onetime activity as and when a new project comes up. Project Manager or Project Lead prepares a project plan for the complete project while earmarking milestones to be achieved thereby measuring project movement towards its closure. Well said and done, if an organization or project team lives on this project plan till the completion of project without measuring the actual achievements scored at a shorter and prescribed frequency, it could lead to a disaster.
That is where project plan monitoring comes into picture where during regular project review meetings the initial plan is measured against the actual tasks completed at their stipulated time. It is a well-known fact that a delay in meeting one deadline for release of a milestone or completion of a task has recursive negative impact on project overall. That is why a regular review is very important and a dashboard where plan versus actual timelines against each task is shared with all relevant stakeholders.
Teams engaged in more visibility feel more satisfied and get an automatic momentum and thrust to meet their timelines.