Guide
Shift pattern meaning: 4 on 4 off, continental, Panama and DuPont
Updated
Shift pattern names are trade shorthand rather than standards, and several of them describe the same cycle. Knowing which is which saves a lot of time in a consultation, because two patterns with different names and identical arithmetic will produce identical objections.
The on-off patterns
4 on 4 off, 3 on 3 off and 7 on 7 off all describe a run of working days followed by an equal run of rest days. All three work half the days in the cycle, so on 12 hour shifts all three average 42 hours a week and all three need four crews for continuous cover.
What separates them is human rather than arithmetic. A three day run is easier to recover from than a seven day one; a seven day run gives whole weeks off. The 4 on 4 off cycle of eight days rotates through the calendar so that weekends fall differently each cycle, which is either the attraction or the objection depending on who you ask.
2-2-3, often called Panama
Two on, two off, three on, then the mirror image in the second week. It is a fourteen day cycle that works seven days in fourteen, so on 12 hour shifts it averages 42 hours a week, the same as the simpler on-off patterns.
The reason it exists is the weekend. Because the cycle is exactly a fortnight, the pattern lands on the same days every two weeks and gives every crew a full weekend off in alternate weeks. That predictability is what people are buying, and it costs nothing in hours.
Continental and DuPont
Continental patterns are the family that rotates crews through mornings, afternoons and nights on short runs, usually on 8 hour shifts, in a cycle of four or eight weeks. They exist to spread the unsocial hours evenly rather than to concentrate them.
DuPont is a four week rotating cycle on 12 hour shifts, built around giving each crew a stretch of seven consecutive days off once a month. It averages 42 hours a week over the full four week cycle, which is the point at which its arithmetic can be checked: measuring a DuPont pattern over a single week tells you nothing.
The name to distrust
Any pattern described only by its shift length. "We run 12 hour shifts" says nothing about the average week, which can be anything from 36 to 60 hours depending on the ratio.
The two numbers that decide everything are days on and cycle length. Ask for those first, and the name becomes a label rather than a claim.