Does a modern destroyer need higher strategic mobility more than a very high tactical top speed?
Short answerPotentially yes. A useful future design could combine an economical cruise setting with a higher efficient 'super-cruise' setting for sustained strategic movement.
NotesIntegrated electric propulsion allows designers to think in terms of how much speed one, two, or three prime movers can efficiently sustain rather than treating propulsion as a single cruise-versus-maximum choice. One proposal uses two efficient speed bands: ordinary cruise and a faster sustained transit condition. That arrangement would improve a destroyer's ability to reposition over operational distances without requiring extreme top speed for every tactical maneuver.