I think the "years in the making" line comes from the fact that the seeds for this story were first sewn in the opening arc of Superman/Batman. Yes, I know, that was only two years ago, but it's still more than one year. Isn't DC logic wonderful?
It might go back further, but I'm not sure.
And just to clarify, while Zero Hour set the "10 Year Rule," that was extended to 12 by a Secret Files issue that came out in 2000. It's also generally accepted that 4-5 years of real time equals one comic book year, so technically we're at 13 years now.
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Yeah, I know. Too much time on my hands.
