Additionally, Lebanon makes me wonder if there's a confounding factor here. Lebanon being a Muslim-majority country, many Lebanese take at least part of Friday off as part of their weekend. Having a standard three-day weekend company-wide might sidestep issues of UK/US workers wanting to meet on Fridays when Lebanese workers are unavailable, and Lebanese workers wanting to meet on Saturdays when UK/US workers are unavailable. This prevents people from being in the office on a Friday or Saturday and twiddling their thumbs while waiting for input from somebody in another country with a different weekend standard.
Actually Lebanon is not a Muslim majority country (demographically it now is but politically no - power is shared between Christians and Muslims ) and they work a standard M-F week, unlike the gulf. We based in Lebanon for our Middle East operation because we liked Beirut better than Dubai, it’s cheaper, the talent is great, and we had some founding customers there (a bit strange but go figure). It’s been a great decision for us and we hope we’re helping throw off the stigma of Beirut being a war torn city just s little bit.