Working N hours in unusual schedule is different from working N hours in usual schedule and then being on call. With the former, you get some compensation, for

Working N hours in unusual schedule is different from working N hours in usual schedule and then being on call. With the former, you get some compensation, for example you may work on Saturday but have a free Monday. Depending on your priorities, it may actually be a good deal -- there are things you can do more conveniently when you have a free Monday. With the latter, it's "when you're at work, you're at work, and when you're at home, there is still a tiny voice in your head remininding you that your boss could call you at literally any moment". This may limit the ways you spend your free time, for example you can't go to places where it would be impossible or very inconvenient to get quickly online when called. And generally, you just can't make promises even about how you spend your free time. For a sufficiently large company, it should be possible to find a few people willing to take an unusual schedule, and then the company could be covered 24/7, with every employee able to turn off their work phone the moment they leave. It's just... more convenient for the managers to do it the other way round.