taberstruths - 12:03 pm on Nov 11, 2012 (gmt 0)
I have a theory. After watching my own site and what happens with serps, and then listening to all of you and your observations over the last few months, I have found some correlations.
Thursday/Friday has seemed to become the day that Google does something with their algo that gets mentioned a lot. Thursday - Sunday seems to be when there are more complaints about the quality of the serps being really bad.
On my own site which is not e-com but informational, I have noticed that at least 3 out of 4 weeks per month search drops significantly on Thursday, only to pick back up at previous levels either Saturday night or Sunday. The only exception to this is when they run some other large algo change earlier in the week like Panda.
My theory is this. We know that Google has been testing/implementing/has implemented an AI component to their algo. I believe that this component runs on Thursday through Sunday during the days they have less traffic. Each time it runs, it tests or targets a certain type of linking pattern by temporarily giving those types of links or pattern of linking more juice than would be normally given. This causes the crap sites "dross" to rise to the top. This results in the crappy serps we all see on these days. It then "learns" what type of linking patterns or other targeted metrics are associated with crappy sites.
This is an age old method of purifying other substances, I think they have applied it to their index. Cause the dross to rise to the top, then skim off the impurities.
At least that is my current theory.
Search was down from Thursday afternoon until Saturday late evening approximately 30% This is a regular occurrence.