The Cube was designed to mimic draft experience close to that of an unstable draft.
The 4/2/1/1 distribution allows each card to appear enough times per draft as you would expect in normal pacts. This cube has 615 cards. 600 cards plus 15 for one extra pack due to Summon the Pack so that breaks down like so:
So you can draft the normal 3 packs per player and have a significant amount of chaff left in the "shoe" as to ensure each draft isn't the same each time you play the cube. Or you can power up your draft by drafting by adding additional packs (go to 4 or even 5) increasing the likelihood of more uncommons and rares/mythics make it into your deck, but remember you will also increase the likelihood of some of the very powerful commons in significant numbers are there too.
Seeding Boosters Packs