There are spots too, where time is supposed to overlap. Like you could be standing on a battlefield where a battle took place 500 years ago and if the conditions are right, you could see the battle raging around you. *shrugs* It's not as common as like, vampire myths, but it's a neat way to introduce us to the elusive relatives of Sam and Dean, lol. I've been wondering if all their entire family died too, because no one ever seemed to come looking for them after Mary died.