cricket
I tend to pattern my fleet organization by the type/era I am mimicking.
If my inspiration is the Age of Sail, I center the main fleet on a heavy but slow battle line supported by small fast “scouts” plus a healthy dose of mid-weight ships designed for independent cruising.
If my inspiration is WW1 I use the Grand Fleet and High Seas Fleets as a guide. Since the war will be decided by the heavy battleship they make up the core. With the only other threat to the battleship being a fast attack by fast moving Torpedo (missile) Boats I screen the battle line with numerous Torpedo Boat Destroyers. Cruisers and Light Cruisers exist to scout out and locate the enemy line and survive long enough to notify the fleet. And by the way, we have those new fangled Battle Cruisers. Gunned like a battleship but armored like a cruiser. Oddballs for accepted fleet tactics but they are fast fast fast. We'll make them an independent unit supported by other fast units, say Torpedo Boat Destroyers and Light Cruisers.
If my inspiration is the modern navy, then the fleet will consist of fewer ships. But those ships will be highly specialized and deadly in their areas. With a combined battle group being a very deadly force.
Though I don't really do much of anything based on WW2 forward. While aircraft may have completely rewritten how wars are fought in the real world, gaming wise fighters really sucked the fun right out of things. For me anyway.
Following the original subject, there is nothing wrong your fleet composition guidelines. And they can lead to a fun game which is the bottom line here. When I build ships designs I don't usually try to be the most efficient, rather I try to build toward a concept. History is littered with military equipment based on the perceptions of the period rather than the best and most efficient design. In the age of steam many warship designs were rendered obsolete almost as soon as they rolled out of the yards.
If you really want and interesting game, try separate ship building and fleet make-up guidelines. One for each player side. Each based on a different theory of warfare. In WW1 the theory was that the big gunned ship decided battles, later it was the aircraft carrier. Be warned though, this can lead to really lopsided battles even if they are interesting and a whole lot of fun.