Since Pokemon has clearly made it a priority to lessen the value of cards pulled, I might as well throw in some information.
First, I don't know what the number on the inside of the boxes stand for, but all the cases that I've opened have the same number on each box in the case. For instance, the case of Dark Explorers that I opened all had the number: 143760. Maybe it's a case number, maybe multiple cases have this number. I don't know. I'll pay more attention, but I've never seen a case change numbers in the middle of it.
I didn't write down all the cards that were in my cases, but have some information that may help put the runs together. There are 12 cards to a box that are Holo or above. 6 of those cards are on the right side of the box, and 6 of them are on the left side of the box. Here is the wrapping order of these cards in a box:
5-3-3-4-1-2
That means that if you open a pack that has a Holo or better card in it and are at the 5 spot, then you can count 3 packs from there and get another Holo or better. And then 3 packs from there and get a Holo+, and 4 packs from there and get a Holo+ and the next pack will be a Holo+ and in 2 packs there will be another Holo+.
This is a wrapping pattern per side of box. So the left side of a box could have Holo+ cards in packs:
5, 8, 11, 15, 16, 18
OR
2, 5, 8, 12, 13, 15
OR
1, 4, 7, 11, 12, 14
etc...
This works for both sides of the box and is independent of each other. The left side of a Dark Explorers box always has a non-full art EX at position 5. The right side of a Dark Explorers box always has a non-full art EX at position 5, a full art EX at the second 3 position, and if it has a secret rare it's at the 2 position.
As you can see, the right side of a Dark Explorers box is clearly the better one. All the other positions will contain holos. All the pack in between these positions will contain rares.
Sometimes there are slight errors, but overall, this is the pattern. Below is the raw data from my Dark Explorers case, starting with box 1 (if the front of the boxes are facing you when they're sitting in the case) and ending with box 6. Obviously the numbers on the left are for the left side of the box and the numbers on the right are for the right side of the box. Italic and Underlined are regular EXs, Bold and Underlined are Full Art EXs, and all three means Secret Rare.
I jacked up the left side of the first box by forgetting to write down some of the holos that I found.
5-2-5-4-?-? / 2-1-2-4-3-6
2-5-3-3-4-1 / 2-5-3-3-4-1
5-3-3-4-1-2 / 2-5-3-3-4-1
4-1-3-1-5-4 / 3-1-2-6-3-3
5-3-3-4-1-2 / 2-5-3-3-4-1
5-1-2-1-6-3 / 4-1-2-5-3-3
As you can see there are exceptions, but the overall pattern is there. This same formula held true for Next Destinies as well. Even with this information it's still not profitable to buy boxes for resell unless you were getting the boxes for $66 or could sell the "worthless" packs unopened. And that's before they nerfed the prices of EXs with the tins.
Anyway, hope this pattern helps place random packs that people open.