I have been observing for a long time that does dofollow links plany any role in increasing Google crawl speed. Answer?
Just not like that both links are crawled fastly by Google but some more important is given to the dofollow links
Do follow links are to make link juice pass and to improve ranking of your site. When you have more number of links pointing to your site then its possible that search bots do arrive to your site through those links thus increasing the bots activity in your site.
Google's crawl frequency depends on relative importance of your website. Relative importance is based on number of pages and number of incoming links your website have. So if your website has lot of incoming links the importance of the page increases, thus it leads frequent crawl by SEs.
Dofollow links are always very helpful in SEO. Dofollow links from quality pages in help in easy crawling and indexing of pages.
Dofollow is the highest "weight" links you can get for the search engines, but no follow are still good for anchor text and keyword matching. Really just make sure to have quality PCRobots.txt, sitemap and a fast loading website with quality w3c verification. This will keep Google crawling your site asap and giving you the most benefit and trust.
Google's crawl frequency depends on relative importance of your website. Relative importance is based on number of pages and number of incoming links your website have. So if your website has lot of incoming links the importance of the page increases, thus it leads frequent crawl by SEs.
it makes no affect in speed of crawling of one site. crawler is multi-threaded. it is not indexing just one site at a time.
Your activity will increase which is why it is even more important to be updating your content everyday.
That doesn't really make sense to phrase it in such a way. A "dofollow" link is just a plain hyperlink, in other words, a link absent the rel=nofollow link element. A "dofollow" link would be the standard to judge against, so you wouldn't say it gets crawled faster. Nofollow links don't get crawled any differently, they just often don't get indexed.