I suspect that the maxima change over time, probably expanding - not just because of technological innovations [as author Greg Costikyan discusses throughout the presentation] but also because of cultural innovations. And to some extent the two form a feedback loop - pop culture [at least in the West] seems to have a much richer vocabulary for dealing with time, surely the result of cinema. I don't think Dickens could have written the script for Groundhog Day - perhaps H.G. Wells though...