Often I'll see webmasters and SEOs say that they see a huge spike in GoogleBot crawl activity on their web sites and thus, they are expecting to see an update in the upcoming days. I always found that to be interesting, I mean, I can see the logic there - but there is really no evidence to show this to be true.
So I asked Gary Illyes from Google on Twitter if that is a truth or a myth and Gary said a myth:
@rustybrick myth— Gary Illyes (@methode) February 11, 2016
Google said for site moves, including HTTPS migrations, they will crawl your site faster but that is just an indexing thing. The algorithm updates are not always attached to indexing.
So I guess those that feel an increase crawl rate shows signs of an upcoming algorithm update are potentially wrong?
This has been a theory in the SEO community for a really long time, I am surprised I haven't or no one has asked Google about this to date. Or maybe I missed it?
Forum discussion at Twitter.
Update: Gary brought up this question in an interview he did today with Eric Enge and explained it in more detail:
Here is the video: