Reading a schedule that is already telling you it will slip

Milestone dates are lagging indicators. By the time one moves, the causes have usually been visible for weeks in float consumption, resource histograms and permit throughput.

Reviewing those three signals weekly, against the plan rather than against last week, gives a project team time to act while options are still cheap.

The intervention is almost always resourcing or sequencing, and almost never a revised end date on its own.