Why Mogami's 155 mm turrets may have fired slowly

Why did Mogami's triple 155 mm turrets not match the rate of fire of leading foreign 6-inch guns?

Crowding may have hurt performance, and the planned 8-inch conversion may have reduced the incentive to perfect an interim turret.

Mogami's 155 mm rate of fire lagged contemporary American, British, and German 6-inch weapons. Crowding inside the triple turret may have limited its performance. A more speculative explanation is that designers already expected to replace the mount with a twin 8-inch turret and had little incentive to perfect the interim weapon. If so, the original battery functioned partly as a treaty-era placeholder. That explanation remains a suspicion rather than a settled conclusion.