It is often impractical for detailed schedules to span very far into the future. Many things can change and it is often better to restrict detailed planning to the next stage or tranche and leave subsequent stages or tranches at a relatively high level.
The Gantt chart below shows the first stage of a project (ST1) with its component detailed activities (A - E) with subsequent stages (ST2 – ST4) only planned in summary form.
The term indicates that as time passes, the threshold for detail moves like a wave rolling through the project or programme.
