I've read enough science fiction based on this principle that I'm semi-comfortable with kiloseconds, megaseconds, and gigaseconds (roughly a quarter hour, a ten

I've read enough science fiction based on this principle that I'm semi-comfortable with kiloseconds, megaseconds, and gigaseconds (roughly a quarter hour, a tenday, and a third of a century, respectively). I'm not sure what the "myria-" prefix really adds to the mix. The people that are objecting on the grounds that it doesn't fit the "natural" unit of the day (or month, or year) are missing the point: metric is all about picking units regardless of any convenient lineup to anything, and then applying them to everything anyway. As a matter of usage, most people take this concept even further and always count from the next smaller unit even if the larger one is closer: thus you rarely hear of "half litre" but rather "500 mL", not "quarter metre" but "25 cm" or "250 mm". Basing metric time on seconds makes vastly more sense from this perspective.