I'd imagine that most people have issue getting them to work well. You don't really get two side mounts for the price of one...at best, you have 75 BBs (assuming a 1.5 unit rotate) to cover both sides, instead of 50 per side. If you have the extra .5 units to put into a rotate gun, it would also give you a 75 on one side and a 50 on the other. So, yeah, you can cover both sides with one gun, but you can only do it for half as long and you are giving up a lot of potential below the waterline hits....to gain...what? The one I had in my Courageous worked fine, but the ship itself was so terribly suited to fast gun combat I could never get my two stern guns on target, which effective left me with a 1 unit ship to cover both sides. I'd have been a little bit better off with single fixed guns, one on each side.
How do you get a gun on each side while retaining a stern gun, if the ship only has two after turrets? Can you mount a gun in a casemate or secondary battery? I seems like a good tactic to have both sides covered so the enemy can't sneak past to the unprotected side of your stern (assuming he's chasing you.)
I use a bow turret. Very few ships only have 2 turrets. If someone tries to get to my unprotected side, I turn and hit em with the stern gun until they realize it's a bad idea.