A screen needs interlaced positions so that weapons can cover the same approach from different ships. Hunts could help against submarines and aircraft, while larger destroyers were better placed to face a surface attack. The Hunts could start inside and move outward when a submarine contact called for them. Using the inner ships first helped the outside destroyers keep their depth charges and remain able to defend the screen.
Notable Point · 1:14:09-1:15:31
How Hunt-class escorts fit into a layered screen
An inner escort could move out to prosecute a submarine contact while the stronger destroyers kept their places on the outer screen.