In the early days, Google would update its index only once a month, but over time they have gradually changed how their algorithm works and they now update their index much more frequently – to the point where the “dance” is a much more subtle movement.
Instead of a huge number of websites seeing their rankings increase or decrease on a specific day, changes are generally much more subtle.
However, there are still some occasions when a phenomenon similar to the Google Dance of old may be seen. For example, when Google rolls out an algorithm update such as the Penguin or Panda updates – or even a massive change such as Hummingbird – which was essentially a rewrite of their old algorithms from the ground up, this has a massive impact on the SERPs.
Because of this, the term Google Dance still persists, albeit with a slightly corrupted meaning.
One thing that many webmasters fail to understand about the Google Dance, and the way that Google operates in general, is that Google’s index is spread over thousands of servers that are located in more than a dozen different data centers.
This is why when you try to find out what your Page Rank is you may see different answers depending on when you look it up and where you are in the world at the time. In fact, there are many services that will query all of the datacenters for you and show you the individual results.
Google does not roll out changes to the search results and page rank to every server all at the same time, so during a period where the index is being updated there may be some people seeing old results and some people seeing new results.
Google sometimes uses this to do informal testing, rolling out new ad designs or new anti-spam techniques to small geographic areas to test user response. As a webmaster, this can make tracking your marketing techniques difficult, but it can also offer you a little advantage if you are able to keep on top of changes. A knowledgeable web marketing service can provide valuable insight and keep your website ranking no matter what animals Google unleashes.
So that when you hear about a new change – such as the removal of authorship profile photos in the search results, you can make plans to cope with that change before it goes live.