How earlier warships change every theater cumulatively

Would earlier battleship deployment mainly affect the Atlantic, or also the Mediterranean, Indian Ocean, and Pacific?

It affects them all because earlier capital ships arrive alongside carriers and cruisers, changing reinforcement and maintenance choices throughout the fleet.

Extra ships alter what can be maintained, concentrated, or released elsewhere, so their effect cannot be confined to one theater. Earlier capital ships change the Home Fleet, while earlier carriers and cruisers reshape the Mediterranean and eventually the Far East. A larger carrier pool could keep Eagle and Ark Royal in better condition instead of repeatedly extending the same scarce hulls. The result is cumulative fleet availability rather than a one-battle bonus confined to the Atlantic.