The goal for the conveyor belt is to have one loaded carrier with support ships in each of 4 locations.
Carriers are nice, but not even required for this strategy to succeed. In fact, in some ways I think the US is better off with more light forces and yes, even some CAs. As I posted elsewhere, a pretty good US ‘standard’ build is 2 DDs, 2 SSs, 1 CA, 1 TRs, 1 Inf, 1 Art for 54 IPCs. This gives good flexibility for attack, defense, and island raiding as well as potential to hit convoys and act as blockers.
Cost for cost:
1 CV + 1 Tac + 1 Fighter = 37 IPCs for 4 hits, 7 attack points, and 9 defense points. But note that you cant even use the CV to soak up hits unless you have friendly base nearby (which is not always possible when ‘raiding’).
For 3 IPCs more you can have the 2 DDs, 2 SS, 1 CA for 5 hits, 11 attack points, and 9 defense points. You also have 1 shelling option to support invasions and far more convoy hitting potential as scattering ability. The downside is that you lose some of the flexibility of playing games with LBA basing and you are restricted to naval bases to retain a 3 space strike range.
That is not to say that CVs dont have their role, but honestly I like having the ships for sea threat and the planes available for LBA duty.
The idea behind the CAs is that they offer the ability to magnify the strength of invasion forces. If Japan has 2 Inf garrisoning an island, they can feel pretty comfortable about holding out against a single Allied TR attack (either a 3/1 or a 2/2). Japan has odds in that battle and as the Allies, you are relying on luck to succeed (a long-term plan for failure IMO). But if there is a CA or two floating around, that threat potential goes up. NOW a 2 unit garrison is NOT sufficient in most cases. Yes, the Japanese COULD get lucky and hit twice and prevent the invasion but that is about an 11% shot…not something I want to rely on. In addition, the CAs just add to the headache because they run decent odds of hitting attacking units (50% more effective than DDs). So if a CA-led invasion hits an extra enemy defender and draws a heavier resposne from the counter-attacking forces then it’s more han made up it’s +4 IPC cost over a DD IMO.
Again, it’s all about escalating threat against Japan. The more places Japan is threatened, the more places she has to spread out to defend or suffer the consequences. A few CAs simply increase that threat at a relatively cheap cost.