Excerpted from the Critical Path Method (CPM) Wikipedia page.
The essential technique for using CPM is to construct a model of the project that includes the following:
- A list of all activities [in Value Flows, those would be Processes] required to complete the project (typically categorized within a work breakdown structure) [this could come from the Dependent Demand explosion],
- The time (duration) that each activity will take to complete,
- The dependencies between the activities and,
- Logical end points such as milestones or deliverable items.
Using these values, CPM calculates the longest path of planned activities to logical end points or to the end of the project, and the earliest and latest that each activity can start and finish without making the project longer. This process determines which activities are "critical" (i.e., on the longest path) and which have "total float" (i.e., can be delayed without making the project longer). In project management, a critical path is the sequence of project network activities which add up to the longest overall duration, regardless if that longest duration has float or not. This determines the shortest time possible to complete the project.
How to use CPM: prioritize all of the processes on the critical path. Delaying any of them will delay the whole project. Delaying some other process beyond its "float" might put that process on the critical path.