...and get adviser Ricci from High Council, who gives another +5%)
You can also attribute Ricci's bonus directly to Mussolini, in this case you do not waste a political advisor slot. Its what I do if I keep Il Duce around, which is again, what I do in most of my games. No game as Fascist Italy really feels like a good experience without Il Duce.
You can also combine a lot of other factors like Incrociatori Pesanti / Incrociatori Leggeri but these come so late during early naval race they are largely irrelevant in my book (you will be trying to improve industry / land units while completing political focus - I rarely have time for air / naval focus apart from the 35 days focus that give a lot of dockyards). Pre-For Blood Alone DLC, I also used Naval Production Focus from Continuous Focus. +20% extra naval dockyard is huge. All of them combined can provide a serious advantage specially for battlecruisers / super heavy battleships. You will be producing them much faster, and these ships usually take ages to produce.
Don't forget concentrated / dispersed industry tech either! Each tech level gives a flat +10% production bonus, and full 100% stability can also give +20% production bonus.
So, I build only new SS and refit old ships. That's my program. Its usunally enough to beat UK in Mediterranean in complex with army and airforce.
On the other hand, me (personally) like CRDA more. I like make heavy armored ships and refit 0 armor CL toward armored with highest armor level.
I rarely refit ships nowadays. Its rarely a good thing, but if you are smart with the pieces you are refitting, and keep costs low, its good. Don't replace stuff like engines and armor, as it will increase costs so much it won't make sense. Its much better to build a new ship in such a case, because you keep the old one... and get a new one... In terms of production / time wasted / raw combat points, its what makes sense. If you upgrade a Zara class ship (which has level 2 armor) to level 3 armor for instance you will be paying something like +3500 production. Which is insane for a refit that provides such a miserable combat advantage. Its pratically 70% of the price of a proper light cruiser!
I also rarely fight in the mediterranean. In many games I declare war on Yugoslavia in early 1937 before France revokes guarantees. Paradrop a few divisions across French cities right in the first week of the war, and France instantly capitulates. What you get is pratically all of french holdings... AND... the french fleet. HA. Now you can put them to proper use and show the brits who has the most powerful fleet in the world! Also you can puppet Czechslovakia and annex Austria while you are at it, and prepare for a direct showdown with Hitler - in order to show that the Duce will not tolerate being in 2nd place!
As for CLs - I have to confess but in general I rarely do CLs with a lot of heavy armor. In many case scenarios, you lack the steel so lvl 1 armor is enough, specially since you are trading speed and production costs for a tiny bump in armor and hp. If you got steel, go ahead. As long as the cruiser is not naked, its good already in my book. Cruiser armor is always small so heavy attacks will always pierce it. Therefore, Cruiser armor is largely just to prevent light attacks from destroyers, so any armor will do. I don't know if naval battles changed, but this used to be the case years ago. Most of the real damage will be sustained by the battleships. Thats partially why I don't go crazy with battleships / super heavy battleships and add more than 2-3 heavy turrets. You want these ships mostly for the big hp / armor values (they will be in most cases the primary targets so more targets to soak damage - the longer your cruisers can operate).
There are many opinions on the topic of course. But just like in the past amongst theorists, one thing still holds true. These ships are irrelevant in many cases during a war, and a huge investment in money / production costs. You cannot take land with ships, for instance, and in many cases they will just end up somewhere like Scapa Flow. In the pocket of some... british empire... Or as the new home/hideout of some fish!
CNA has one BIG advantage - it works for all types of vessels. So, it gives bonuses and level up much faster. When CNA has level 6 (and you can buy additional bonus), CRDA would be level 4 or even 3. Also, CNA bonuses are very sweet, as shown above comments.
You are right with CNA, but who cares about destroyers and submarines (carriers are not even part of the equation because per major fleet you are only using 4 or something like that). These ships (destroyers, subs) rarely need bonus. And as Italy you are probably going for mass production instead of good quality. So bonus for these become pratically irrelevant, since you will be replacing them in quick order, at least its what I do. I always find mass production submarines (as long as you have range to operate near Cape Verde / Canarias / Azores, where I usually keep subs raiding) much better, and for escort duty, you will probably also want numbers instead of quality vessels as well.
CRDA gives bonus to all cruisers and to battleships. What else do you want? These will be (or should be) the main fighting force. You don't fight fleets with submarines or destroyers. You fight them with light cruisers (for mass light dmg), heavy cruisers (when you want less production costs and heavy attack) or battlecruisers / battleships (for mass hp / armor / heavy attack). So the bonus are given to the ones that need them (carriers are obviously also important but you don't spam build those as stated previously).
The only real advantage is that you level it up faster, but you shouldn't be over producing destroyers / submarines early game, in any case. Focusing on a couple of carriers and/or on light cruisers (or on completing many of the ships already queued on game start) is what most countries should do. Refit is also genius if you are smart with it, but it requires micromanagement (oh god so many ship classes!) and I rarely have patience nowadays for that.
In some cases you can also go for super heavy battleships, but the countries capable of doing them (without great sacrifice) are the exception and not the norm. Super Heavy Battleships were already hard to produce in the past, but after paradox decided to lock them behind a secret project that requires a specific facility and hard-to-obtain points to conclude, they are usually not viable to pursue early on. Also these (or similar) capital ships require a lot of steel / chromium, so unless you steal these from someone else, like Yugoslavia / France, be prepared to pay the price.
It will depend on your playstyle or if you want to try something new. In the past, I also went with panzerschiff (for example) for raiding, and I was really perplexed at their capability. Their mass range allows you to place them deep in the atlantic, but you will need to produce a decent amount of panzerschiffs in order to have sucess (and also to keep an eye in case the main british fleets comes hunting you and you need to retreat manually, which might be a hard thing to do if you are running the game at max level 5 speed all the time). But why go for panzerschiff if you can go for carriers + cruisers/capitals and beat the uk's fleet on a man-to-man fight directly. In many cases you don't even need to build a single ship, because AI is AI. I gave the example of panzerschiff but I could give many others as well - at the end of the day it might not be the best option available, but it sure is gratifying.
