I remember reading this exact piece of advice, but have been trying to remember where.
Would anybody be able to provide the blog post I believe we both read, which says almost exactly what Iv wrote? I could have sworn Michael Nielson wrote it, but I was unable to produce it last time I searched. So I am following OP's advice and am asking here. :P
I may have found the post by Michael Nielson I was looking for... on Hacker News!
https://news.ycombinator.com/item?id=666615
In particular, this piece of advice he gives still rings true to my ears:
Often, when struggling with a book or paper, it's not you that's the problem, it's the author. Finding another source can quickly clear stuff up.
The author sometimes forget to mention what B actually is, changes the meaning of the multiplication operator implicitly, assumes the formula given is inside an integral.... I could go on.
A maths article is an article. A lot are imperfect, quite a few are bad. Some times it is not the reader that is lacking.
That being said, do your homeworks and only consider that possibility after giving the article one hour of your time or so.