Study says workers are only productive 3 days a week. Time for longer weekends?

A new study has shown that office workers are only productive for three days a week. Research shows a poor night's sleep is the biggest cause of an unproductive day, followed by being too hot in the office and being surrounded by distracting colleagues. On a typical working day, 15 minutes are spent gossiping to colleagues, 14 minutes are spent looking at no-work related content on the web and eight minutes are spent making teas and coffees for co-workers. So if workers are only productive 3 days a week would it make more sense to extend the weekend?