Extensive links from the same site with the same anchor text can ruin our efforts? or it will help to boost up ur ranking!
It depends on the site too here. If the links are from a site which search engines trust as good then you will have a favor. However you may rank for that anchor text well but not have other keyword major benefits. I guess you are asking this question keeping in view DP forum in mind. If so that's my answer
Getting links from different websites is a lot better compared to from just one single site as then your backlinks are from different IPs and it is helpful to have links from different domains. You get links from different PR sites, different anchor texts, so all these things help your site with ranking for various keywords, you site is not just about one single keyword.