I've often felt that a 5 day work week is about availability , not raw productivity. I could easily compress all of my weeks work into 30 hours or less, but that's not what my managers and clients value. What they value is the fact that I'm making progress on my tasks, and that my reachability is not preventing anyone else (people above me or below me) from making progress on their tasks
One thing my colleagues always value that I’m willing to respond at any time. It means most people come to me with their problems and my value to the business has increased (removing blockers from others).