I don't think that's necessarily true, in fact I think what happens more often is the idea of a 4 day work week is dismissed by people such as yourself as it doesn't equally apply to everyone. A 5 day work week as is common now doesn't work for hospitality staff, for example. Does that mean that we should all work 4pm-3am Saturday shifts because that's when nightclub staff work? Of course not. do we argue that because patients in hospitals require 24/7 care that we all take up 4on-4off 12 hour shifts?

The argument for the 4 day workweek is that _many_ jobs would be performed just as efficiently as if they were 5 days per week, so they might as well be. If there was a compelling argument that hospital patients required 16 hours of care per day rather than 24, you can bet people would be suggesting dropping doctor and nurse shifts to 4x8 or 5x8 rather than 4x12 or whatever insanity they're doing right now.