Businesses use around 300 variations of 12-hour shift patterns, and the most common are called The DuPont, 2-3-2 and Four On, Four Off. Each pattern has its own benefits and drawbacks and is suitable for different types of organizations.
The DuPont system is most common in chemical, power and manufacturing industries and has seven or eight straight days off in every 28-day rotation with three- or four-day work stretches. Oil refiners use 2-3-2, which involves a 14-day pattern of two days on, two days off, three days on and three days off and usually includes every other weekend off. Four On, Four Off involves working four days or nights in a row with four days off.