When companies expand from working 5 days a week to 7 days a week, they start by having the current employees work overtime on the weekend. Over time, however, management faces a tough choice:

1. Continue to rely on weekend overtime. To avoid alienating the current workforce, management can continue relying on weekend overtime to meet demand. Unfortunately, the situation will eventually become worse with excessive costs, lower productivity, quality and safety issues, and personnel problems such as increased absenteeism and turnover. By the time management realizes this, employees will have become addicted to the overtime and it will be difficult to change anything.
    
2. Hire a weekend crew. The company can keep the current employees on their Monday through Friday schedule and hire new employees for a weekend crew. Because it's difficult to find and retain good part-time employees, companies usually hire a full-time weekend crew that works 12-hour shifts on Friday, Saturday and Sunday. Double coverage every Friday is expensive. So is the common practice of paying the weekend crew for 40 hours instead of the 36 hours they actually work. Less experience on the weekend crew results in lower productivity. Personnel that work weekends often do so to get their foot in the door. After a year or more of waiting to be hired, they may get frustrated, leading to increased turnover and absenteeism. You can read more here: https://www.shift-schedule-design.com/Blog?m8:post=weekend-crews.
    
3. Adopt a 24/7 schedule. While the two options discussed above minimize the impact on the current workforce, they have some serious disadvantages. They might be safe from a labor relations perspective, but the cost can be considerable. The best way to avoid those costs is to adopt a 24/7 schedule. I've previously recommended a process to follow:  https://www.shift-schedule-design.com/Schedule_Selection_Process. I've also discussed incremental steps to take: https://www.shift-schedule-design.com/Expand_from_5_to_7_Days. For examples of different 24/7 schedules, please check this out: https://www.shift-schedule-design.com/Schedule_Examples.