Rank seems to have been very volatile lately and there has been reports of unconfirmed updates on the 11th, 14th, 15th, 17th, and now, the 19th and 20th.
In addition to these unconfirmed updates, there has been reports of sites that are seeing massive crawl spikes from Google bots, which led some to believe that the increase in crawls and the algorithm updates could be related.
On Twitter, there were speculations that the increase in crawl rate signified an update.
John Mueller responded that the increase in crawl rate and algorithm updates are unrelated. There is always something launching, they are always working on improvements, and any increase in crawl does not signify an update.
He later on added that if they want to launch an update, they have to test it and prove that it’s good first. They can’t do that if they have to recrawl the whole web just before going live. Crawl rate is not an early warning signal for updates.
The whole thread for the Twitter discussion can be accessed here.
With regards to why some sites have experienced a spike in crawling, there could be a variety of reasons for it.
One of it is that there could be some big site changes that has the crawlers visiting the site for a refresh crawl, or content has been released more often which led crawlers to visit the site more often, in order to crawl fresh content.
Despite there being a variety of reasons why there could be spikes in crawl rates, looks like an algorithm update is not one of them.