Reliable task completion provides for reliable task releases. We use PPC (percent of plan complete) as the measure of reliability in the Last Planner System™. When a task doesn't complete as promised we call this a plan failure. Investigate the cause for each plan failure. Do this at your daily or weekly meetings in conversation with the performer or last planner. Don't be satisfied with the first stated cause. Get to the underlying issues by asking 'why' five times. Develop and use standard reason codes to categorize your data in a Pareto format. Remember this is about learning and improving not about assigning blame.

Post the Pareto data alongside of the PPC chart in the location of your project team or last planner meetings. Update this chart as you are discussing your weekly work plans and daily or weekly performance. After a while patterns of plan failures emerge. When you see at least five instances of a reason for failure, then stop and perform problem-cause removal.