- Based on weeks. The number of complete weeks it takes before the pattern of work repeats.
- Based on days. The number of days it takes before the pattern of work repeats.
The first is the most commonly occurring, but on occasions the latter will be used. The first definition has the advantage that over a shift cycle each team / employee will work the same number of social and unsocial hours, and these will be equitably distributed over the days in a week.
For example, each employee will work the same number of Saturday Night shifts and Monday Day shifts, etc.