Why the KGV battery used a 4-2-4 arrangement

Why did the King George V class use a 4-2-4 gun arrangement instead of 3-3-4?

The design began with twelve guns; weight and reliability problems led to replacing one quadruple turret with a twin.

The original intention was twelve guns in three quadruple turrets. Weight and reliability difficulties led to a twin turret replacing one quadruple mounting, producing the eventual 4-2-4 arrangement. This explains why the design did not begin with a ten-gun combination of two triples and one quadruple. A later explanation uses rough counting analogies to show how each extra gun introduces both its own possible faults and interactions with neighbouring guns. The formulas illustrate mounting complexity without establishing calculated failure rates.