Why more cruiser guns can mean less firepower

Why would the Royal Navy favor triple six-inch turrets over quadruple mountings for a larger Town-class cruiser?

The quadruple turret's complexity and congestion reduced its rate of fire enough that a faster-firing triple mounting could deliver as many or more rounds.

Quadruple turrets add machinery, crowd the working space, and create more ways for faults and crew interference to slow the loading cycle. Four guns firing eight rounds per minute are compared with three guns sustaining ten to twelve rounds per minute. The triple mounting could therefore equal or exceed the larger turret's volume of fire while remaining simpler and more reliable.