Google: Adding Too Many Pages Too Quickly May Flag A Site To Be Reviewed Manually

Google’s Matt Cutts answered a question submitted by another Googler, John Mueller, on YouTube asking, “Should I add an archive of hundreds of thousands of pages all at once or in stages?”
The question is, if you build out a new section of your website with tons of content – is it safe to just launch them all at once or should you do smaller chunks at a time?

Matt said that Google can handle it either way, but he did say that if a site released hundreds of thousands of pages overnight, it may raise a red flag and warrant a manual review by the Google spam team. And if you do not want Google to manually review your site and you don’t want to draw attention to your site – you may not want to release too many pages too quickly.
Here is the video: