I was able to do the problems till ~ problem # 1600 fairly easily, means complete ~ 50 problems in an hour or so with a success rate of 90+ %. After problem # 1600, the problems are not only taking a long time (10 - 15 minutes) to solve, but I am also getting 30 - 40% wrong.
I started with Mate in 1s, done them in 3 days. Then, I started the Mate in 2s, been doing about 50 - 75 everyday for the past several days.
Anyone knows the answer to my question in the 1st post?
I am guessing the puzzles in the book differ in rating. It looks like the puzzles go harder as we go through. Does anyone have a clue of classification of the difficulty of the problems? Did any reviewer try to rate them?
(Example: 0 - 300 problems are for beginners rated below ~ 800 USCF , problems 300 - 600 are for ~ USCF under 1000 etc etc)
I am talking about this book
http://www.amazon.com/Chess-5334-Problems-Combinations-Games/dp/1579125549