A warship's shield is four faces: bow, stern, and both sides. Each face is its own barrier. A hit on the bow does not reset the stern. A face that has just been struck needs a moment before it climbs back. Put the fresh face toward the guns and let the tired one recover. Captains who live do this without making a speech about it.
While a face is up, it flattens whatever hits it. Splash, drill, and the clever shape of a warhead all become one blow against the bubble. A torpedo that meets a live shield wastes itself on the curve. The cutting is for hull, and only for hull.
A face that is basically dead should not still be a wall. Let it drop, and let it climb. A scrap of leftover barrier that eats a whole volley is a bookkeeping trick, not a shield.