When learning a new opening, do you learn the opening every time you encounter a new variation or do you try to learn them all at once?
When learning a new opening, I tend to stick to a line which suits my style. At first, I will play strictly to the book and usually end up in traps, getting a piece horribly out of position, or with a pawn structure that prevents defending myself. After a while I begin to realize the traps that are associated with the opening and can avoid those. Eventually I will have my pieces in the right alignments, usually by the 8th move or so. And after a long time, I will have become used to setting up the pawn structure so that I am well defended by the 15th move.
Once those basics are covered, I will begin to look for places in those first 15 moves where I can get in a simple tempo changer, like a bishop check, so that I can castle with tempo, or perhaps there is a nice trap somewhere. This is just me though, I am not sure how everyone fares with learning new openings or if they just pick them up right away.
An example of this situation for me was the English (1. c4 .. 2. Nc3). I really enjoy this opening, but figuring out how and when to advance the e and d pawn took me a while to learn. As did figuring out if or when I should fiancetto, or advance the f pawn after
0-0, or how to avoid a kingside pawn rush, etc.
As for the question of learning all the lines. I did not, I just learned the one which I felt was similar to my tastes, and then learned all the nuances to that one, including its transpositions to other similar lines. Sometimes I have noticed the English can transpose to the London, which I enjoy.
Specifically about the article you link, I agree that playing towards an outdated but proven trap can be beneficial, but I honestly doubt your opponent is going to play that exact line. So in the mean time, you will have to deal with all the other facets of the opening you only learned the one trap for. Note that the author states "All you need is a desire to learn new stuff.". I think that is the key to learning an opening. Learn the main line you like, and then play it for a while knowing you are going to get cheap shotted, trapped, blocked, out of position, and be in a funk while learning it. Once you get over having all that happen to you, then you will have that shiny polished diamond.