[lukeschlather]

The 3.2 million number is highly suggestive:

    3263847/(365*6*24)
    = 62

It sounds like they've been running an integration test which uploads an image once per minute for pretty much their entire existence (they're a little over 6 years old.)

This is sensible. It's the only way to get instant feedback when the site stops working for any reason.

[tgb]

The sampling was done only for the old-style 5 character URLs. They've since moved to 7 character URLs. Depending on how that 3.2 million number was reached, you maybe should be calculating rate using just the time they were at 5 character URLs. I don't know when the switch occurred though.