This ship is interesting reading. Again, great model and thanks for prompting a little research.
There's a bunch of problems associated with firing multiple guns next to each other from close by. Captain Mac knows a LOT more of this stuff, but a couple of basics are that there's a need to stagger the timing by a second or so, otherwise the shells can run into each other.
On this ship, the 15 inch guns were in pairs, although there was some thought put into the design of the gun rooms to separate them in order to minimize damage in a catastrophe.
But the pairs of guns exhibited a problem with wake effect between the shells, and weren't set up to fire in sequence, at least according to wiki.
But she served as a unit for the Allies 1943-1945, and wasn't decommissioned until 1967.