And the magic number is...

[Chickenboy]

ORIGINAL: USS America

It "worked" because the IJN never again had as many as 6 CV's operating together after Pearl.  Midway was the last time even 4 operated together.  After that, they no longer had the numbers to do so, even if they wanted to change their operating doctrine.  

"Shattered Sword"'s authors had a great quote about strategic objectives in the Pacific: In the Pacific, there were only two strategic objectives: those that required all of the carriers in the Kido Butai and those that required none.

The Japanese made innumerable mistakes diluting their carrier firepower in the war. I am grateful that, in the game, the Japanese do not have the same scattered approach to the carrier war and can operate their carriers together ad infinitum.

[USSAmerica]

I'm not grateful about it, but I do get your point.  [:'(]

[zuluhour]

Simply put the Allied player needs to be prepared to evacuate and run like the dickens from any major port the KB decides to visit.

Danke Herr Bolter, As a newb, This has been my strategy scince December 8th.

However, I did not apply this rule to sea encounters until May '42, where upon I now apply this doctrine to ports and mid ocean intercepts. Enterprise and Hornet lie in 200 fanthoms.

[Cap Mandrake]

I'm not sure I accept the mathematical certaintly implied, though it certainly seems plausible that that a 2.5/1 ratio might keep enemy strikes on the ground.

One trick is to set some Zeroes on naval attack or perhaps on sweep with commander discretion. They seem to go in first and "soak-off" allied fighters and cause fatigue. One could also put some Sallys (or other such disposable aircraft) at the nearest Jap base and give them a certifiably insane CO so that they go in first and eat ammo.