There already is a shorter format. John Isner and Nicolas Mahut took 3 days to complete a match at Wimbledon, Isner eventually winning 70-68 in the fifth. And Isner cost Kevin Anderson any chance he might have had of winning Wimbledon when their semi went something like 24-22 in the fifth. Now all Slams have a final set tie break at 6-6. If men in their 20s can't handle 5 sets they need to work on their fitness