How do overruns and delays materialize overnight?
They don’t. But the reporting system for many projects hides problems until they become out of control. In addition, usually the only reporting that occurs happens when there is scheduled meeting or when a severe crisis develops that impacts the timeline. If you have a project with daily, weekly, or monthly reporting, and have surprises, tighten up on the reporting timeline; tighten up on the things you measure. Initiate early reporting on key indicators, as well.