Still think its a form of testing and sharing going on. The site I manage has an 11 year history and nowhere in those logs are there swings like this. Last week it was Tuesday and Thursday where orders came in as fast as we could update. This week it was Monday and Wednesday. During those periods conversions go to almost 10% which is 10 times normal.
My impression is they are testing different times and days for each site among other things.
SERPS are still struggling. For clear transactional inquiries google is sending me to pages where I can only get quotes or information. I'm sure t will cycle through.