“There is no limit in the Act on the number of hours employees aged 16 and older may work in any workweek. The FLSA does not require overtime pay for work on Saturdays, Sundays, holidays, or regular days of rest, unless overtime is worked on such days.”[1]
“In general, federal mandatory overtime laws follow guidelines set by the Fair Labor Standards Act (FLSA). The FLSA establishes the primary regulations for overtime pay affecting employees working in the private sector, as well as in federal, state, and local governments. The FLSA outlines the following guidance about overtime:
-Nonexempt employees must receive overtime pay for hours worked over the 40-hour workweek. -Pay for overtime must be a minimum of 1.5 times the regular rate of pay. -There are no limits to the number of hours employees 16 years old and older can work during a workweek, other than the fact there are obviously a finite number of hours in a workweek. -Overtime pay is not required on weekends or holidays unless overtime is worked on those days.” -Employers may penalize employees who refuse to work required overtime. Though the penalties can vary by employer, there are no federal guidelines for employer penalties on employees refusing to work mandatory overtime. In some cases, employees may be subject to discipline, reassignment, demotion, or even discharge. -Employers can require nonexempt employees to work beyond their 40-hour workweek hours without any notice, such as requiring employees to work another shift without any notice.[2]
So basically there is no limit to how much an employer can ask their employee to work mandatory overtime, as long as they are paid for their over time hours at a minimum of 1.5x rate.
[1]https://www.dol.gov/agencies/whd/overtime#:~:text=There%20is....
[2] https://blog.namely.com/mandatory-overtime-laws-for-each-us-...
I work in a industry that is not at all related to any type of emergency services, supply line or transportation sector. People in my industry still regularly work at minimum 50-60 hour work weeks and very often 70-80 hours a week (in often relatively physical jobs). We are usually guaranteed a turn around time of 10 hours (how many hours we can have between our shifts— which is really just 8 hours if you factor in travel time), and that is only because our union recently fought for that in our last contract negotiation.
US labor laws are still very much the Wild West of labor laws.