You must understand that it is more about the quality of links rather than the quantity. Even if you are building 1-2 links but they are quality links, you will be doing good rather than having dozens of low quality spam links.
I haven’t build a lot of backlinks to those articles. Some of them have 2-3 backlinks. The best ones have 10-15 backlinks only. And I’m not the only one saying this. There’s a recent article at SEOMOZ explaining how a guy achieved this with 13 backlinks. All of them with different anchor text.
The Number of Referring Domains Has a Very Strong Influence on Rankings. You may have heard that getting backlinks from the same domain has diminishing returns. In other words, it's better to get 10 links from 10 different sites than 10 links from the same domain.