At some point, I think in the last few years but don’t recall the source or the time, I encountered the idea that experienced duration of a unit of time is determined by the proportion of one’s experience that unit of time represents. If you are three years old, a year is nearly forever. If you are thirty years old, a year is rather short. The basic idea that units of time seem shorter as you age is a cliché, but connecting that to the proportion of one’s total experience represented by that unit of time seemed like the kind of observation that was unexpected and novel but should have been a cliché universally acknowledged.

Connecting to the previous post, one might reasonably assume that the number of repetitions needed to convey legitimacy is inversely proportional to the number of repetitions one might have experienced, given one’s age and the duration of the phenomenon.