Why quadruple gun turrets proved troublesome

Were French quadruple turrets more successful than British designs?

They were more reliable than the British quadruple mountings, but triple turrets remained easier to balance, arrange, and maintain.

French quadruple turrets appear to have been more reliable than British examples, but still less dependable than triple mountings. The Royal Navy rejected a proposed quadruple six-inch turret for HMS Belfast and HMS Edinburgh after constructors and commanders argued that it would not work reliably. Four separate ammunition feeds and their supporting machinery either demanded a very wide installation or became tightly packed and difficult to maintain. Adding one more gun could create disproportionate engineering and availability problems rather than a simple increase in broadside weight.