Renown's triple four-inch mounts survived because replacement was costly

Why were Renown's criticized triple four-inch mounts not replaced sooner?

They were awkward rather than unusable, so the Royal Navy waited for a major refit instead of paying for an earlier peacetime alteration.

Later criticism can make the triple four-inch mounting seem worse than it appeared during the First World War. The closely spaced guns were difficult to load, but their problems did not outweigh the cost and disruption of replacement before a major refit became due. Peacetime planners therefore tolerated an awkward system that remained usable. The example shows how navies retain imperfect equipment when its defects stay below the threshold for expensive reconstruction.