No offence Tarquin, but what's the purpose of this test? It cannot possibly tell us anything about our own sites, or the sites we work on.
Like many of us, I've already tracked the time it takes for Google to index the changes to my own sites - about 14 hours. I work on sites that the Google robots hit only once every 2 weeks - less content, and fewer updates, though some of them earn 10 times what my more 'frequent' sites earn.
Good O, Hacker News! Which means sweet F all to me, all of my customers, and pretty much everybody else on the planet.
By the way, how long IS a piece off string?