I would say the best descent and approach is one flown with the power levers at idle, speed at a constant Vman clean until FL100, thereafter 250Kts all the way to your first configuration point. Once you advance the props for landing, the aircraft looses speed in a jiffy, so what ever you can manage.
Its a fine balance between fuel efficiency, passenger comfort and personal ability. Find the balance, and you will always be on the safe side.
Sn