LEARN. PRACTICE. GROW.Understand the concept
An activity network shows precedence. In an example without additional resource constraints, A takes 2 days; B then takes 5 and C takes 3 in parallel; D takes 2 and starts only after both finish. Minimum duration is 2 + max(5,3) + 2 = 9 days. A-B-D is critical. C has 2 days of float in this model. Shortening C by one day does not shorten completion. If B and C need the same person full time, the parallelism assumption no longer holds.
Apply and decide
To make the network executable, add calendars, change windows, availability, and external dependencies. Person-day effort measures work, not elapsed time. A four-person-day task at 50% availability needs about eight working days if work is distributable and there are no other blockers. Record these assumptions. When trying to bring a date forward, identify the constraining path and the cost or risk of changing sequences and resources.
Workplace application
Draw the plan as a small sequence before loading it into a tool. In the example A=2, B=5 and C=3 in parallel, D=2 after both, duration is nine days under the stated assumptions. Reducing C does not change that date while B dominates. Then add the shared specialist and contractual approval; the logical network alone does not prove feasibility.
A firewall change lies on the critical path of a migration. Adding developers to documentation does not remove that dependency. Confirm the network window, owner, and prerequisites before communicating a recovered date.
Common pitfalls
Adding parallel branches; ignoring shared resources and calendars.
Related topics: Technical decisions and executive communication · Plan effort, capacity, and forecasts
The critical path depends on the model; availability and windows can change the real plan.
Reference: Schedule Assessment Guide · DR Technical Project Manager 2026.4; independent professional curriculum