I agree for that. No need to over complicate things more than necessary, but for we should at least try to mimic print runs in a generic fashion.
General Algorithm can be like this: (15 cards)
1 R, 3 U, (1 Land/Special Slot), (1
Foil from
Time Spiral on), Rest C
We can estimate some of the early sets like this:
Arabian Nights = 2 U, 6 C = 8
The Dark = 2 R/U, 6 C = 8
Antiquities, Fallen Empires, Homelands = 1 R, 2 U, 5 C = 8
Alliances, Chronicles(if we care?) will follow the general Algorithm but only have 12 cards total.
Time Spiral uses the Special slot for a Timeshifted subset.
I know that Revised could have basic land appear in a Common or Uncommon slot, but we should probably just ignore that.
Some other things to complicate matters:
Mythics - starting in the Alara block Mythics replace Rares every 1/8th of the time. We should make sure we have enough Mythics per set before we start doing this since, otherwise they will appear too often.
Foil - Starting with
Urza's Legacy Foils started to appear about 1/6 packs. Originally, they would just replace the same rarity slot that they were (which means no functional change for us). But starting with
Time Spiral they would change to replace a Common slot. Timeshifted foils still sit in the Timeshifted slot, so there's no functional difference for the subset.
Since we can't represent Foils I'd put that at the lowest rung of priority, and if it gets done eventually great, otherwise it won't be noticed.