There should be a maximum on weekly working hours to prevent employees from being overworked. Workers need to be able to rest and have a private life outside of work. Employees that are on salary would be even more unfairly treated because they would be overworked and not get extra pay for it.
I do not believe that there should be a legally mandated ceiling on weekly working hours, because i see no reason for this to mandated. A person should be able to work, and earn as much as their employee allows them to. Mandating a limit serves no purpose to the public.