This structure is good for engagements that have long duration (like >3mths) and high intensity.. a lead, an heir and a spare covering a key "role" means that y

This structure is good for engagements that have long duration (like >3mths) and high intensity.. a lead, an heir and a spare covering a key "role" means that you have continuity if someone goes sick or gets another job. The project can just keep rolling along!