The fleet role of battleship secondaries

Should a battleship rely on its main battery against cruisers and leave lesser targets to its own fleet?

Fleet roles matter, but combat is untidy: secondaries address likely secondary threats when escorts are absent or cannot keep them away.

Battleships cannot assume they will fight only battleships while cruisers handle every smaller opponent. Fleets operate under imperfect conditions, so a capital ship needs a secondary battery suited to likely secondary targets. The primary battery is designed around the ship's principal opponent, while the secondary battery covers threats that may still reach it. A battleship forced to fight off close torpedo vessels shows that the fleet screen has failed.