Hi,After Yamamoto was killed, did the japanese immediately think to change their code procedures? If not then, when?

While the Midway attack was being planned, the Japanese were resolutely going ahead with Operation MO, to take Port Moresby. Isn't this a wonderful example of the famous Japanese talent for dividing their forces, since the planning also called for a divertionary attack at the Aleutians?

Thank you.

Herb