Sgt_Kickaxe - 7:07 pm on Jun 21, 2012 (gmt 0)
They don't need much time to rate a page anymore, perhaps 2-3 days tops, at least for an established site.
As evidence I can offer affiliate links. I have several pages that do well with a particular affiliate program however that program occasionally lowers its payout for several days in a row. While the payout is low I turn the affiliate links off. When the payout returns I re-activate the links.
Google sends this page traffic when the links are off, a good deal of traffic(it's a great page), but when the links are active the traffic is cut 75% within 1-2 days and doesn't return until 2-3 days after the links are removed.
Couldn't happen without frequent sampling.