I read a rumor that Miracle Day was originally conceived as five episodes like CoE, but the network wanted five more. That might explain why the plot didn't show till episode seven.
The pilot movie for Monk has the same problem. It was obviously originally scripted as a single hour, and Monk still spots the golden clue at about the fifty five minute mark. But then Shirona calls to quit, and he gets distracted; and we get a second hour before we learn what the clue was.