Continuous 24/7 or semi-continuous systems are usually based on either 3 or 2 shifts with, typically, average shift lengths of 8 or 12 hours respectively.  Points to consider when choosing a shift length:

  • 12-hour shifts are sometimes considered to be too long - there may be issues regarding fatigue, health and safety and productivity
  • The European Working Time Directive puts a limit of 8 hours on the night shift for "hazardous" work
  • 12-hour shifts require fewer attendances at work which saves staff travel time and cost


Example 1: 5 teams, 24/7/365 system. An average of 146 and 219 rostered shifts  under a 12 and 8 hour system respectively, a difference of 73 shifts per year.

Example 2: 4 teams, 24/7/365 system. An average of 183 and 274 rostered shifts  under a 12 and 8 hour system respectively, a difference of 91 shifts per year.

  • 12-hour shifts lead to longer periods of usable time off as a result of having more rest days (see examples above)
  • 12-hour shifts lead to more weekends off


Example 1: 5 teams, 24/7/365 system. An average of 31 and 21 weekends off under a 12 and 8 hour system respectively, a difference of 10 weekends per year.

Example 2: 4 teams, 24/7/365 system. An average of 26 and 13 weekends off under a 12 and 8 hour system respectively, a difference of 13 weekends per year.

  • 12-hour shift patterns are usually more "attractive"
  • 12-hour shifts require just two handovers a day rather than three under 8 hour shifts.
  • 12-hour shift patterns have longer rest day breaks which sometimes are considered to be too long from a communication and continuity point of view
  • 12-hour shift absence cover: a shift can be covered by bringing in somebody from a rest day. This is also the case for 8-hour shifts but there are fewer staff on rest days to choose from
  • 8-hour shift absence cover: a shift can be covered by bringing in somebody from a rest day. It can also be covered by extending adjacent shifts. For example, a late shift can be covered by a 4-hour extension of an early shift and by bringing in a night shift 4 hours earlier. This is not an option with 12-hour shifts.

Mix of 8's and 12's

There are advantages and disadvantages of using 8 or 12 hour shifts. As a compromise, some organisations use a mix of 8 and 12-hour shifts. Typically, 8 hour shifts are worked on weekdays with 12 hours at the weekend. This maximises the number of weekends off but for most of the week 8-hour shifts are worked.

We sell lists of shift pattern examples  for continuous and semi-continuous operations based on 8, 12 and a mix of 8 and 12 hour shifts. Please contact us for prices or advice and a quote for devising a shift pattern based on your requirements.: