The interval that needs no arithmetic
Every other span on the bench reports a projection: a count scaled up or down to a minute. Sixty seconds reports the count itself. Nothing is extrapolated, nothing is assumed about whether you could have held the rate, because you either held it or you did not.
That makes it the only reading worth comparing against a published average. The figure quoted most often — around 384 CPM, or 6.4 clicks per second — is a full-minute figure, and holding it against a five-second peak is how people convince themselves they are far above average.