A lot of those feeds update infrequently. And there are a number of duplicates (a pain in Google Reader to administer) or the same site that migrated from blog platform to blog platform, but I declined to remove the old feed (primarily for search, though in the past few years, Google Reader search got nerfed to only retrieve from current year and a smattering of older items by an algorithm I ascertain could only be random or happenstance).

But the main gist is that I only read a small percentage of links. It is mostly a river I wade in, though, if I have the time, will go in-depth. It's why search is so important -- it's a "google custom search" method (yes, I know there is a CSE product in Google Labs, but it's even more flawed) that limits my queries to those sites I have pre-declared an interest in.