Symptom: Estimates of the primary group are realistic, but ignore efforts of people outside their immediate group.
Projects often require efforts of people beyond the immediate "prime contractor" group. If so, projects may be delayed by other people -- team members who become the "critical path" and cannot deliver their piece of the project on time.
This is typically the result of a project leader who did not line up the necessary "subcontractors" before committing to a project deadline.
Every subcontractor must participate in the estimation process, and be prepared to make the needed time available. If they do not, the project will be delayed awaiting the right talent from these other groups. As a result, teamwork break downs and projects take longer than expected.
Another (more generic) way to state the problem is as follows:
