100% agreed, I think it's hard to define relevancy anyway. Is a link from a site about pigs, in an rare article about birds, relevant for "pigs"? Is a link from a site about pigs, in an article about birds, relevant for "birds"? What has to be relevant? Whole site? Just the content around the link? Now, thinking further, isn't a site about hiking relevant for "boots"? Is a site about the sky relevant for "rain"? Is a link from a local business directory relevant for "plumber", even if it's the only plumber in the city, but there are 100 lawyers in the directory?I will not buy anything that says " Links have to be niche dependent".
if links only count 1/3 as much, then create 3 times the links. 1/3 X 3/1 = 1.
If we knew we'd all be rich.
I don't know that there is a set percentage of backlinks that should be followed. The quality of the backlink may be the most important factor in SEO. So don't worry about percentage. Build high quality backlinks.