Often you'll see the SEO forums light up a bit before an algorithm shift, where SEOs say, wow - GoogleBot activity on my web site is unusually high. This leads people to think an algorithm update may be coming soon. Sometimes they are right, but often not.
Meaning, I see a lot of this (GoogleBot activity) chatter lead to nothing - not even people reporting traffic or ranking changes.
That being said, Josh Bachynski asked Google's John Mueller if a Penguin or Panda algorithm would trigger a deeper crawl. John said no, it won't.
John said this twice, first at 6 minutes and then when I asked again at 55 minutes in. John said:
That would probably be completely separate from an algorithm like Penguin or Panda. That's something where usually their technical signals that we pick up on when we kinda like re-crawl sites, in a big way.And those are the kind of thing for we kinda look at what we've seen from the recent crawls and kinda recognize that something significant has changed. And say oh well maybe we should check the rest of the site as well.
So it's not so much that quality or web spam algorithm would say we should recrawl this website but its more like we see significant changes on this website so we say okay well let's take a look at what else changed.
When I asked again, he said point blank "I don't think we do that."
Here is the video:
Forum discussion at Google+.
