LEARN. PRACTICE. GROW.Effort, availability, and duration
Effort measures required work; duration measures elapsed calendar time. Someone allocated at 25% can deliver, on average, 0.25 person-days per working day. Twelve person-days require roughly 48 working days at that allocation before leave, dependencies, and interruptions. Adding people does not automatically shorten tasks constrained by sequencing or scarce expertise.
Build a plan that shows dependencies
Identify predecessors, calendars, shared teams, and decision milestones. A purchase with a four-week lead time may dominate the schedule even if installation takes one day. Explicitly reserve operations capacity using historical data and team agreements. When incidents consume that reserve, update the forecast instead of hiding the impact in subjective completion percentages.
Actual cost and cost to complete
Keep the approved baseline and a current forecast. In currency units, a cost forecast can add actual cost and estimate to complete: EAC = AC + ETC. For effort control, separately add consumed and remaining person-days; do not call that total a financial forecast without applying rates and other costs. Include external effort, licensing, cloud, migration, temporary support, and retirement work as applicable. Explain variances through causes, impact, and decision options.
Workplace application
In a role with 75% support and 25% project work, use agreed availability and actual interruption data. Eight working days at 25% availability provide only two theoretical person-days. If six remain, show the four-person-day gap and options. A second person needs competence, context transfer, and owner agreement; this does not automatically double output.
The team has consumed 32 person-days and estimates another 18. The forecast is 50. If the approved budget was 44, the forecast variance is +6 person-days. Reporting should explain the cause and offer options without silently changing the baseline.
Common pitfalls
Confusing effort with duration; assuming unagreed extra capacity.
Related topics: Lead decisions and communicate what matters · Prepare the change and hand over autonomy
A credible commitment combines effort, availability, dependencies, and an updated forecast.
Reference: Schedule Assessment Guide · DR Technical Project Manager 2026.4; independent professional curriculum