Turning Office 365 off at the weekend

There's so many variables there, I don't see how it would be realistic to expect the company to block employees from accessing Office 365 when they're not on the clock. Maybe it's manageable for a small business, but what about a company with 5,000 employees and a 24x7x365 operation? Maybe you get the regular work week sorted out, but then there's holidays, vacations, sudden family emergencies. Just thinking about all the extra support calls makes me shudder ("my schedule got switched, but I'm locked out because I usually have this day off").

I think the better route would be to have a company policy that states that employees are required to turn off any work-issued devices before ending work for the day, or if they're using a personal device that they must log out of their work accounts before the end of their day.