Improper assignment can cause enormous overtime costs and substantial employee discontent. One person can staff a single shift for five days a week. That is, normally a person works five days a week, eight hours per day.
Nobody works every day of every week of every year.
People are absent for vacation, sick leave, and many other reasons. When a work assignment that operates five days a week must always be staffed, additional people are required when the primary person is absent. Typically, 1.1555 people are needed to staff a five-day work assignment that must always be staffed. Then a scheduled relief person must staff the work assignment when the regular person has their two regular days off per week. In addition, like the five day work assignments, provision must be made for staffing work assignments when the regular staff is absent.