The way I’ve been introduced to it (informally, and with the cardboard variant), during sprint planning everyone gives an estimate of how hard a particular issue/task will be.

Note that it was not said how long. These are specifically not supposed to be units of time because “someone with experience might do a 13 in 10 hours, while a beginner may need 20”.

And it’s Fibonacci because… I don’t know, I’m sure there’s an official explanation about that choice of distribution but it’s basically an attempt at witchcraft to me.

You know that thing about the Spinal Tap amp going up to 11 so it can be “one” louder? That’s how I feel about those cards. In practice I had a much more sane version of this in another team, and that was just “this will be very easy to do”, “this will take time” and “this might be too complex for the benefits”.