Thank you Don for the info about USPCC. Clearly I was not updated.
But the real question is: what keeps big companies from announcing a number - like 2500 decks - and selling 5000 or more decks?
That's why I like numbered decks. On those cases I know what I am buying.
On other cases it's difficult to be sure mainly because what Encarded already appointed in this thread: the marketing of big companies is deceiving, is not clear.
(Sorry for any english mistakes - I hope you get the ideia)
It's not really in their best interests in the long run to get caught. It would destroy the company's reputation. It's not to say it never happens, but I'd say it happens with "wiggle room" numbers.
By that, I'm referring to the fact that a USPC print run can end up +/-10% the run size contracted for. This is a standard clause in their custom deck contracts. If it's over, you pay for the extra; if it's short, you get refunded the difference for decks not printed. The odds of any print run being precisely any given number are practically impossible. But then again, most companies do also account for keeping a reserve of decks.
The reserve is used for premium giveaways, company gifts, replacements for damaged or misprinted decks, etc., and this number is usually not counted in the advertised totals because they're not an actual part of the release other than in cases where the deck is only given out as a premium release, like Gold Arcane and LTD.
It's one of the reasons why there's no actual figure for how many White Centurions were created - it appears that T11 ordered a thousand, but it's known that the print run went over by an unknown amount within the contracted "buffer margin", leaving the actual number of decks made between 1,000 and 1,100. They either kept inaccurate records of how many they received or were disinclined to release the actual figure. Regardless, they're all gone as of last year anyway - they gave away the remainder of the reserve during a Black Friday promotion.