How would Force Z benefit from a full destroyer squadron escort?
Short answerIt would help, especially if the destroyers were modern enough to add effective anti-aircraft defence rather than merely more hulls.
NotesA full destroyer squadron would benefit Force Z. The decisive issue is the choice of modern escorts with useful air-defence weapons, rather than the number of added hulls alone. More ships enlarge the screen and create additional anti-aircraft firing positions. Older destroyers without effective air defence would add far less against the attack that historically destroyed the force.