Ok, so this would basically be like setting-up contingency battles. If you win the first battle, your mechanized/air units held in reserve (didn’t participate in battle) could move through the newly conquered territory to perform an attack. I would probably also allow mech to drag an inf or art with it into battle. I think this is pretty good, and units don’t get to pull double duty.
You would still leave your expensive units exposed though attacking deep into enemy lines, so should all ground units be allowed to move 2 spaces in NCM to help protect your gains (part of my original post). This would take some planning and maybe some limits could apply?
Because it would be a powerful tool for the attacker (can’t picket as defender), maybe a defender retreat should also be considered after each round of battle (I think air should for sure be given a def retreat option)
As for navy, yea I think something like this could be done there too, but a defender retreat option would be needed.