One Carrier would be (sorta) too easy to keep track of. You'd really need a bunch of em to be able to sneak up on someone. Cover enough area(s) to be a menace. You'd need a free-ranging, self-sufficient, Battle-group, or two, or three to be scary
To threaten an enemy (their plans) you really need to come out of nowhere, be where he doesn't expect you to be...with power.
It would've helped by delivering air-power out of the range of current land based resources, but then again would've used up other resources for her protection. The proverbial double-edged sword.
I believe their best ability (if they had the correct aircraft/enough fuel) would be to search areas of the ocean to direct wolf-packs to targets early on. The subs could definitely do more damage....if they could find them, and be directed (in mass) to intercede.
If they see you (the one Carrier) coming, or know where you're going, it's possible for them (your adversary) to make a mess out of your grand scheme.
Even Yamato had a sister.

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