sven,
The zones are phased with electric power for two very important reasons:
1) The power is used to disbond, not melt. If the ice is actually melted, it could run back and actually freeze on a rearward position past the heated mats, and be stuck there for a long time. The flash of energy sent to the mats must be right to disbond, and not to melt. Since the ice accretes at the nose and then deposits aftaard, if the nose is kept clean, no ice grows very far aftward.
2) the shed ice must not hit the tail rotor or any place on the aircraft, so it is shed to the side, which requires precise phasing of that flash of energy. A movie of the aircraft flying in icing conditions behind the tanker shows it sequentially tossing ice off to the sides as the aircraft moves forward, a very impressive sight!
The deice is sized for flight into extreme icing conditions, far worse than military requirements.