A bit off-topic here but I think learning peripheral information has become a norm. Last year I was trying to learn Data Science and completed the "specialization" from Coursera. But then there were sometimes when I was unclear on certain topics being discussed by blogs I followed. So I tried googling to see how to really learn in-depth about Data science. I landed on this page: http://www.quora.com/How-can-I-become-a-data-scientist

The detailing given in some of the answers meant I had to go back and strengthen some of the basics and learn things in depth rather than peripheral information.