Lab_Rat - 7:49 pm on May 3, 2012 (gmt 0)
We removed over half of the URLs on our site and 301'd them on Thursday the 26th. These URLs had mostly thin and/or very old content.
Our Google organic traffic started climbing at 3:00pm on Friday the 27th, and has been between 30% and 40% up every day since. I was assuming the lift was related to the Penguin update on the 24th (assumed it just took a few days to fully roll out). No totally ruling that out, but now knowing that Panda 3.6 hit on the 27th, it seems that may be the cause. The only thing I wondering is what % of the changes we made on the 26th Google would recognize by the 27th?