We all known , that from time to time, google will do an in deep crawl to all our pages it can found of our website (even if it's won't list in SERPS 10% of them) How and when Indeep crawl occur?! Do it occur every 30 days!? When it's occurring, it's occuring for all the websites at the same time period, or there is continuously in deep crawl process... the cycles of in deep crawl is it PR related?! or content change related? or adding new links related? (Just asking... because web directories don't get to much in deep new crawls , even if they add new pages, and new links every day)
It depends on how often your site gets crawled anyhow. Some sites get crawled often, others very infrequently. There is no one set frequency for all sites.
Yeah google sitemaps has a feature where you can tell google how fast you want your site crawled. But I think google deep crawls about every two weeks. Thank You
You seems to be so much interested in Google algo. Why not apply for Google as an Engineer. Indeep crawl will be succesful if you have SE friendly pages. Make sure they are interlink properly so that Google bots can crawl your site. And also yes inlinks with high PR is also related in crawling websites. Hope that makes sense.