Tons of links form the same site?

I have a question about backlinks from the same site:

My competition on search engines has sites with with fair on site SEO but I could see they recive thousand of links.I was scared at the beguining but then I see that all their links comes from at most 20 or 30 different sites...

It's clever to try to compete with those sites making hundreds of well anchered tect links from diferent sites or those thousands of backlins are really difficult to beat?

A hundred links from one site don`t mean much these days cause it would be really easy to manipulate google if they did. So I think 3 quality backlinks have more value than 100 links from some average website.