Why fleet-carrier air groups organize around blocks of eighteen

What would the Royal Navy gain and lose with a 30,000-35,000-ton CVA-01 alternative?

It would be a useful carrier of about Audacious size, but an air group near thirty-eight would fall short of the roughly sixty aircraft needed for robust defense, strike, and support cycles.

The proposed smaller CVA-01 alternative would resemble an enlarged Invincible or an Audacious-class carrier and might carry roughly thirty-eight aircraft. The operating model assigns about eighteen aircraft to each major cycle: air defense, strike, and anti-submarine or support work. Within an eighteen-aircraft block, four can fly, four remain on alert, four prepare at shorter notice, four undergo maintenance, and two serve as spare airframes. That pattern supports a practical group of roughly fifty-four to sixty aircraft. It also explains why nominal deck capacity matters less than whether the ship can sustain simultaneous operational rotations.