User blog comment:D.Dragon123/Why Haoshoku haki is useless./@comment-5962458-20130114225530/@comment-4156018-20130114230942

He didn't even use it in Whitebeard War. Cody was knocked out due to his fear of dying.

And about the WB ship, he used it just to gain respect from Whitebeard's crew, so that they wouldn't just bluntly start attacking Shanks and get killed by him. Obviously he controls it quite well, why else would he be a Yonko? He even used it perfectly when Luffy was just 7 years old.