tedster - 8:14 am on Mar 13, 2011 (gmt 0)
I certainly agree that sometimes major ranking shuffles happen. I'm not so sure about one set time of the month for all sites - at least not any more, now that Caffeine is tuned up.
What do you think makes the big re-rankings differ from everflux? Is it more likely to be a significant algo change, rather than just the processing of new crawl data?