re: When will the U.S. ever wise up and go to a 4-day work week?

I'm not sure how you mix WFH and 4 days? At some point you have to be accountable for certain hours? The few people that just say "I get my work done when I get it done and then I'm done for the day" have no responsibility outside of their own, clients to help, etc. and are more the exception than the norm.

But I agree, there's no reason for most office type of jobs to have a stale 8-5 M-F work week. Companies need to be better about having some sort of flexibility when possible.