The principal obstacle to deploying a American carrier rapidly is the air wing, and what kind of shape its pilots and aircraft are in. With the coming retirement of one carrier, that will leave a total of eleven carriers. One carrier will normally be in long-term rehab and one in short-term refit. So in an emergency there will be nine carriers you can send to sea. One or two of those will have just returned from deployment, and their air wings will be way down in readiness. Having a "spare" air wing means one of those carriers could quickly turn around and deploy again.
While the navy is preparing to decommission one of its twelve carriers, they will keep the current ten air wings. The carriers, and their crews, are actually separate entities from the air wings, their aircraft and support personnel. A carrier, over its lifetime, will operate several different air wings. Although each carrier, even of the same class, is a little different, any of the ten carrier air wings can quickly adapt to any carrier it is assigned to.