Adding Thousands of Pages At Once to a Site - Does Google Counts it As a Spam?

Some large sites like news websites may feel the necessity to add several thousands webpages on the site all at once. Will Google count it as a spam? Well, Google will activate the manual web spam team to have a review of the website. But, in simple words, algorithms can take it as a spam so it is safer to add webpages in stages rather than adding them all at once.

Have a look at this video from Matt Cutts.