Item 4 in our GCTS training framework (See "Theory , Theory and More Theory") calls for the "evaluation, plan of play and standard tactical methods for approximately 250 endgame positions". Keeping this in mind, where can we get these 250 or so positions? Are they documented? do they even exist?
I introduce GM Mark Dvoretsky...
In his book "Dvoretsky's Endgame Manual", the author states that "one should study relatively few positions, the most important and most probable, but study and understand them perfectly...Our basic theoretical knowledge must be easy to remember and comprehend."
Dvoretsky calls these Precise Positions.
In this great book, there sits 213 Precise Positions, indicated by being printed in blue ink. Dvoretsky goes on to say that "these positions should be memorized and which will serve as guideposts again and again in your games". This practical view, enumerating the positions and supplying the ambitious student with the actual positions, suits our training purposes perfectly. This is one of the most vital and important 'russian chess secrets' revealed to us by Mr. Dvoretsky.
This number is certainly ballpark of 250, and given the source of this information, I'm willing to risk my chess future that the study of these 213 positions will result in improved play in the endgame. I also believe that this is an efficient use of study time, and it is important for us to be efficient in our studies, and avoid 'thrashing'. This is one of the primary reasons behind the 4-day training schedule.
Our goal is to take the mystery out of chess self-training and make our job as clear to us as possible. Articulating Precise Positions with regard to chess endings, I hope, gives readers a better idea on what to study and where to get those study materials from. Dvoretsky's book can be had at Amazon.