When I was at uni I tried experimenting with a 30-hour-day, which to me made a lot more sense, since I had enough energy to keep going for more than 24 hours, and could combine sleeping so as to save time overall (ie the time you need to fall asleep and wake up each day, dress and undress, etc).
The practical problem I faced was actually not the Sun routines, since I lived in Coventry at the time (92 hours of grey sky followed by 2 minutes of white sky followed by 89 hours and 58 mins of black sky). My biggest problem was there are no 30-hour watches, so I had to always calculate my own schedule based on the conventional one everybody else was following. It was so much easier to just do what the rest of the world was doing.
I think it could easily work, as long as the conditions were different (could be implemented in the North Pole for example, or on a space station, or in remote areas where everybody agrees, and above all you’d need watches). Would be interesting.