Google's Fresh Crawl
Generally, Google does two types of crawl one is the main crawl and other one is the fresh crawl. The main crawl is monthly based and the fresh crawl can be done daily or at lesser intervals. Google is not too much sure that form which site it has to start crawling and up-to what to crawl. Generally speaking, none of the crawls type add any new page, basically, into Google's main index. It can be done while new or next updation taken place.
If you are looking for the targeted traffic then for some extent the fresh crawls can help you, because the fresh crawl again crawl the pages that are already in the index and selects new pages all alone. Then the evaluation of these recrawled new pages starts that means all new pages can be found just about instantaneously, while they still, are not indexed in Google's main index.
This can be fine for webmasters, however, it is also possible that sometimes few websites suffer because of fresh-crawled new pages push them down the rankings.
It is very common that some new crawled pages increase traffic while they are not indexed in google. And as they are included in the main index, they get their place in the rankings according to their evaluation.
Fresh evaluation is done within a month thereafter, they all are placed in a 'fresh' index and from there they get inserted into the rankings.