Do you think that triangulation is useful?

Isn't dk-Ltd's daily rating 1870?

Yes! Some don't even know the Sicillian (as White).

Actually I misread it

I thought it was 2 wins and 1 loss, but it's 21 wins and 1 loss, so I guess that's a "real" rating.

But still, when I read GOP puzzled over how he's 1800 and doesn't know triangulation I thought "must be 1800 daily"

I had friend who bounced between 1300-1400 OTB USCF and maintained an 1800 daily rating here. I think blitz ratings are more accurate, so that's why I call the OP 1200.

There is simple triangulation, which people here are describing, and a more complex version which you are describing which happens in blocked pawn structures, requires retro-grade analysis(which you seem to describe), and could not be done in blitz. 

Depends on the time control and the player.

Positions that are devilishly difficult, and require tons of calculation, sometimes become extremely simple as a player gets more experience with them and becomes a stronger player overall. I wouldn't be even a little surprised to see a GM pull it off in a blitz game.

Maybe at Karpov's level.  The work still has to be done .  We are all human, even the grandmasters.  Some grandmasters might be able to do it in blitz some not. .  The comments I have read from their books show a lot of time thinking, putting into the correct order.  It takes work.  So I agree with you someone might be able to do it in blitz.

And I agree with you that it depends on the position. Some would be easy, some definitely not!

Simple triangulation can be learned in one session; more complex triangulation(involving blocked pawn structures) , has to be done with a lot of analysis and understanding.  The retro-grade analysis would take many moves and variations, easier to explain than to do.

Yea, I am not 1870, but neither 1200. I am somewhere between those. I play slow, but I am also exceptionally good at solving problems in general. Started by playing daily, but seemed too easy for my style (totally inside my comfort zone and it worked perfectly along with my strengths) . Then moved to blitz to face my weaknesses (playing slow) and there, went to as low as 717. Worked my way up to 1200, by improving my time management and tactics. Now, I am studying endagames and keep improving on my tactics. When I somewhat conquer my nemesis (blitz), I will probably move back to slower time limits. I am doing it the opposite way, but everybody is different.

Actually, what you said (along with a post from kindaspongey) helped me find a new level of understanding for such positions, exceeding once more my expectations. What you said about opposition and zugzwang is totally true and simplifies such positions a lot and if that wasn't enough, I realized that the calculations are very easy and pretty standard. Enemy king moves forward (you get the opposition), moves left-left or right-right (then he gets too far and you invade and promote), moves left-right or right-left (you complete the triangulation and get the opposition) and in the rare cases that does something else, you just invade, using some kind of opposition. Have cut my times in solving them drastically.

Like a lot of chess skills, anyone can learn simple opposition.  As someone mentioned, a lot of chess is skill and training.  Certain endgame positions are a dead win against  even the World Champion, as are certain dead draws.  All this can be taught and practiced.  Yes, lower rated players can learn, for example, the Philidor position in  rook and pawn endings  and draw or the so-called Lucena position and win against the best players.   But chess has so many more skills to learn.  

that was fast and funny . It seems as simple as this now though

I don't remember ever encountering a triangulation position like the one above, but, if I ever do, I think that I have a much better chance of thinking of a move like 2...Ke5 over the board because I have read about triangulation.

Many won ending s are lost or drawn because of lack of endgame knowledge or technique.

Yes.