I’ve worked out a different approach over the years. I have Instapaper installed and when I come across something that I actually want to read but don’t have the time for I just save it there. Tabs and bookmarks are for relevant and important things. Whenever I am in a spot where I’m bored and seeking a good read, like on a train or something, I reach for and rummage through that pile. It’s a big pile, it’s for entertainment reading.

I don’t know about the whole learning only about what you’re focused on approach. I’ve often found valuable insights and lessons in places I wouldn’t have looked at if I were optimizing everything with this level of zeal.