Sweeping generalisation but it is true that most meetings, particularly internal meetings don't need to take as long as they do.
The argument here is that if you reduce the time you allow for meetings and prepare and focus better you can achieve more in half the time.
Has to be worth a try.
For what its worth I am also trying the other stuff suggested, avoiding multi tasking and focusing totally on one thing at a time.
But other things — like most meetings and tactical work — could benefit from compressed time. Often we schedule one hour time slots. Why? How did an hour become our standard time allotment for so many meetings, phone calls, and appointments?