Yeah, I forgot to mention that I didn't factor in the additional 2 packs at the end. (It was just easier without them. Ha ha.) So on top of half of the people getting EX's, let's assume only a few people who DIDN'T get any before pulled one each at the end. Two more booster boxes would need to be used in order to give 36 people 2 packs each, so that's 6 more EX's. In total, assuming nobody who pulled an EX got more than one, that means 24 out of 36 people got an EX. (That's 67% or 2/3 of the people.) So it's possible that this theoretical assumption could explain why the prereleases gave the illusion of EX's being fairly common.
I'm pretty much just trying to make sense of things when people are saying so many people got EX's. Ha ha. But at the same time, I'd like to remind people that pulling EX's won't seem as common outside of the prereleases. In a booster box, 3 EX's out of 36 packs means it's a 1 in 12 (or 8%) chance of pulling one.
Also, it might be possible that some boxes have 4 EX's. But from what I've seen, it's 3. A few pages back I posted a link to TheCatsMeowth's (aka capeter3ncsu's) ND booster box opening. She got 3 EX's in the box. And at my prerelease, out of the 6 people near me who got packs from the same booster box, only 3 of us pulled an EX. (Surprisingly, I was one of those 3.) Again, it's possible some boxes have 4, but so far, I've only seen 3.
Here's the link to that video, in case anyone hasn't seen it and is curious: http://www.youtube.com/watch?v=b0pO5y9QbBA&list=UUohhrJ5lRGoZK9fUX1rAKdQ&index=23&feature=plcp