studying Endgame first, or Openings.

You are not paying attention to what was said: no one was promoting memorization for its own sake. I said understanding every line in your repertoire produces, naturally, and if the brain is capable of it, as a next natural step, memorization. It flows naturally from understanding.

 Understanding comes first, then memorizing the lines that have been understood is the next step. Not understanding all the lines is for the lazy, who want to get by on principles.

  Certainly not enough, unless the brain in question is average.

Well, for me, memorizing and understanding are both hard. Maybe it depends on the person?

Yes, on the brain.

Doesn't it depend on the level of the player, ambitions of the player, etc.? By the way, aren't there quite a lot of near-average brains out there?

"... This book is the first volume in a series of manuals designed for players who are building the foundations of their chess knowledge. The reader will receive the necessary basic knowledge in six areas of the game - tactcs, positional play, strategy, the calculation of variations, the opening and the endgame. ... To make the book entertaining and varied, I have mixed up these different areas, ..." - GM Artur Yusupov

Not for the beginner—which is the context of this thread.

I applaud opening study as much as the next guy, but telling a beginner to learn every line in their repertoire is asking too much—and putting too much emphasis on a specific aspect of the game, when overall improvement should be the primary goal.

Not to mention, a beginner simply wouldn't understand the reasoning behind every line, especially the sharpest ones.

Better to start with principles, then expand to general thematic ideas.

  Apparently my reply to this one went through a glitch...

 Ambitions are fine, but if the brain is average the possibilities will be severely limited.

  Well, firstly nobody should choose a repertoire without understanding the lines being chosen. Taking others’recommendations for a White or Black repertoire should be avoided.

  So it takes quite some time to pick the lines one feels comfortable with, getting at least a general feel for them. Then comes a deepening study of those lines, which literally has no end, for there are so many angles to discover each time you look at them...

Perhaps we agree that, for many brains, it might be sensible to let a lot of time go by between the following of the general-feel advice and attention to the subsequent sentence.

 It doesn’t prove anything other than my capacity to play, not that what I say does or does not apply to others. For that to happen, there must be someone who actually did that profound study, like a student.

 If you want to call what I said ‘nonsense’, be my guest. But labeling it doesn’t refute it. 

 To 152.

  Should that happen, though, in the meantime, one is not ready to play the game, yet.

Is there a reason to only play when considered "ready" by troy7915?

DeirdreSkye wrote: "... What are the odds [that IMPfren and another FIDE certified trainer] are wrong and [troy7915 is] right?"

What about the possibility that the truth is somewhere in between and somewhat depends on the cirumstances of the particular beginner? (Especially a beginner who is not thinking about getting a title or being considered to be "ready" by troy7915?)

Do you have a quote of a claim to know what a beginner needs?

Do you have a specific sentence where "a guy that understands nothing about chess" claimed to know what a beginner needs?

Do you have an estimate of the number of days that are going to go by without you producing a specific sentence where I claimed to know what a beginner needs?

So, thus far, you have no quote that you wish to produce. Since you now consider it appropriate to ask, I inform you that I do not claim to know what a beginner needs. About 36 minutes ago, I brought up the "possibility" that the truth somewhat depends on the cirumstances of the particular beginner.