I'm glad to see someone is talking about this.
My reason? Well, so far every potential shtf scenario I've experienced has garnered a lot of conversation, but I've not heard anybody talk about this... and it's the ones you're not worried about that always bite you in the ass... so thanks to you guys, I now know there's not as much to worry about as there was before I noticed this thread. Because yeah, I think there's really something to this.
Oh, and I didn't take time to read them all, but for those earlier posts that "rolling apocalypse" that started at GMT ... no, I think the timing would be based on what time zone the Mayans were in.