Depends on more factors than that. But in general you might as well make a smaller number of actually decent web 2.0 properties than to make massive bulk of web 2.0s.
Depends on more factors than that. Web 2.0 blogs are very powerful in generating unique backlinks, and boost your search engine ranking as most of the web 2.0 site’s domain have huge authority and weightGuys, if I create every day 10-15 web 2.0 website (wordpress, tumblr, etc.) with one article, link to my primary website and index it, this help my website ranking or harm it?