[juitpykyk]

I've once got 000000. If you do the math it takes about 1 year to cycle through all million of them, assuming no duplicates.

Which makes me wonder, what's the expected repeated distribution?

[kadoban]

This is the birthday paradox. The rough approximation is you need sqrt(n) values to get to a 50% chance of having a duplicate. Sqrt of a million is a thousand, and if they're every 30 seconds, that's ~8 hours or so. So you probably get a duplicate or 2 every day.

There's _much_ better approximations than the sqrt one, but I don't know them and the actual math is too hard.

[jakey_bakey]

Correct, the article actually mentions the birthday problem somewhere. Even with 10k codes (2 days) you get dozens of duplicates, so I'd say it's potentially even more common.

Sextuples are 1 in 100,000, so something like every 50 days (per account).