Then again, showing something that clearly makes no sense, and then refusing to explain it in any way, can't fault people for trying to come up with wacky theories to explain it.
Pretty obvious that Rick wasn't in his coma for just a day or two. Honestly, it looks like it would have taken more than a month for things to get as bad as they did when he woke up. Wasn't just an initial outbreak scenario, things had disintegrated into a pretty set-in zombie apocolypse by the time he woke up.
Not that it really matters, because he wouldn't have lasted a week without the support equipment, IV fluids, etc. "He was just lucky" is equally stupid. Because the writers didn't bother to explain the magic scenario, the viewers are trying...