In every endgame book you will
find the same positions over and over again. Especially the studies of Grigoriev are very popular. That is actually very weird.
Since Gregoriev was always looking for unique positions, the one in a 100,000 kind of stuff. A study book is supposed to treat the common idea's, not the exceptions only.
Take for instance this position of Grigoriev about triangulation.
White to move and win.
I have posted about this position earlier here.
The idea how to play it is clear, I can win it from any chess engine. So that is not the problem. But for me both the keysquares as the corresponding squares are coming out of the blue. I can't formulate a systematic reasoning how you can always construct the right keysquares, corresponding squares and moves. For instance, when the following is played 1.Kc2 Kf4 2.Kb2 Kf5 then the best move is 3.Kc1! I can't stand it that I can't find a sytematic reasoning that even my mother would understand.
I guess that the biggest problem is that in order to work with corresponding squares you have to gather a lot of beercaps, so that your head is not quite clear before you start to think:)