Why alternate gun fits would not simplify Incomparable

Could Incomparable realistically carry twelve 18-inch guns?

Nine 18-inch guns in three triple mountings are considered plausible. Twelve would need a different arrangement, such as quadruple 16-inch or 15-inch/50 mountings, with greater mechanical complexity.

Incomparable has three turret positions, and the design lacks barbette space for a fourth. A twin 20-inch mounting could plausibly be replaced by a triple 18-inch mounting, giving nine guns, but a quadruple 18-inch mounting would not fit. Twelve guns would instead require three quadruple 16-inch mountings, or the suggested 15-inch/50 alternative. Even a very large twin turret uses a familiar arrangement, whereas a quadruple mounting presents a harder engineering problem in this period. Each extra gun adds interactions with its neighbours as well as its own mechanical difficulties.