Independent targeting versus twin-turret redundancy

Why prefer independent gun mounts over a twin five-inch turret?

Independent mounts can engage different targets, while the opposing preference for twin guns emphasizes redundancy within each mount.

Separate gun mounts can engage different targets and retain independent fields of action. That is the reason given for preferring several mounts over adding a second barrel to one turret. Clarke agrees with the value of extra mounts but favors twin guns within them as well, because a second gun can remain available when its neighbor fails. He gives approximate availability figures of 85 percent for a single gun and more than 90 percent for at least one gun in a twin mounting. In the modern systems he has in mind, the guns share the turret structure while their internal weapon mechanisms operate independently.