[quote name='Bones3D']...
So, that probably means the 15 minute changeover doesn't even occur until the very first user who attempts to play within the new 15 min interval triggers a script to compare the last 15 minute flag to the current time, then flags the new time if at least 15 minutes has passed since the last one, and resets the contest for the next user(s).. at which point it likely either pre-determines the minimum amount of time that must pass for that round before it releases the prize to someone, or, it arbitrarily "flips a coin" on every user as they play and then disables the contest after a winning "coin flip" is achieved for that 15 minute period.
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Although I agree with most of what you are posting, they are not randomly awarding the prizes 'on-the-fly' as people make the web requests. ALL of the winning times were pre-determined prior to the start of the promotion. Although we know there is 1 winning 'time-stamp' within each 15 minute interval, the exact distribution within that period was randomly selected and unknown to us.
And, since there is no way to know whether or not the current period's prize has been awarded, there is a good chance that people playing in the later half of the period are wasting their codes since, statistically speaking, the prize has already been awarded. Course, statistically speaking, the people playing during the first half of the period are wasting their codes, too, since the prize time has not yet come.
So, yes, this contest is indeed rigged. And, even though we know how it is rigged, it does not help us much because we don't have instant access to info like when the last person won... Which, of course, they do on purpose.
The system is commonly used by ePrize and PrizeLogic, and is normally quite difficult to predict and/or abuse. However, by not requesting the participants full shipping info at signup, and by not validating the only unique data they do have (the phone number), they have provided a way for participants to make many accounts that are difficult to link/disqualify. The only unique 'data' they have is the phone number, and they are not using that to validate the winners. If, for example, they were to start calling the phone number the winners provided when signing up, to confirm/validate each of the awards, then the bots would be rendered useless (because most people don't have access to hundreds or thousand of unique phone numbers). Or, if they were to start asking for the full shipping address up-front (like ePrize/PrizeLogic), then they could easily disqualify all of the entrants with the same address when they exceed some allowed limit (i.e. 4 accounts per household?).