A schedule is a network, not just a list of dates
Activities depend on one another. Those relationships create paths through the project. The longest path through the network is the critical path under the standard critical-path method; work on it has no total float under the standard interpretation.
Common dependency
Finish-to-Start means one activity must finish before the next can start. Other relationship types exist, but the important skill is understanding what the dependency means operationally.
Float
Float is schedule flexibility. If an activity can move without moving the project's planned completion date, it has some float. A critical-path activity has zero total float in the standard interpretation.
Schedule compression
| Question | Practical answer |
|---|---|
| Fast tracking | Overlap work that was previously sequential; can increase risk or rework. |
| Crashing | Add resources or spend to shorten duration where practical; increases cost or resource pressure. |
Why PMs get schedule discussions wrong
“Can we finish faster?” is not enough. Ask what can be overlapped, what resources are available, what risk increases, what quality trade-offs appear, and whether the shortened date is worth the cost.
Dependencies tell you where a date can break
Dates are symptoms of sequencing. A launch date becomes fragile when work depends on external approval, content readiness, API access or a predecessor task that has no float. This is why dependency conversations often matter more than adding another column to a task list.
Use milestones as evidence
“Design complete” is ambiguous. “Checkout designs approved against the agreed mobile and desktop states” is tied to a decision. “Migration sample reconciled” is evidence that the next phase can safely continue.
Critical path is a management conversation
You do not need to calculate a critical path just to impress someone. Use it to answer a practical question: which sequence of work currently controls the earliest possible finish, and what can we do if one activity slips?
Make eight activities for a website launch, assign durations and dependencies, then identify the longest dependent chain. Move one activity by three days and explain what changes in the launch plan.