At first I thought it would be best to concentrate on the exercises I failed to solve. But when I started to pick up the book I noticed that I didn't remember most of the (1300) positions. For this reason I decided to go through the book again. Not surprisingly my succes rate is now about 95%, and I also solve them a lot faster than I did the first time. I consider this work to be largely a kind of maintenance of acquired patterns.
The other method I recently started is doing 2 Stoyko exercises a week. I have chosen this method to improve my calculation abbilities. Last season I noticed that most of my opponents calculated deeper than I did. So this is probably my weak spot.
Below a description of the Stoyko exercise that I copied from Dan Heismans website.
FM Steve Stoyko suggested this very helpful exercise. First the reader should find a rich middlegame position. You can find them in many Kasparov, Shirov, or Speelman games, or in the books The Magic of Tactics, Genius inChess, or How to Think in Chess. Take out a couple sheets of paper and a pen or pencil.The idea is to write everything you can possibly visualize from the position, like you were playing the game without a clock and you had to see and record everything before you move.
Write down every line that you look at (no matter how bad!), along with that line's evaluation. This should fill up several sheets of paper and take 45 minutes up to 2+ hours! If you chose a sufficiently complex positions dozens of variations should be considered. Consider lines to as much depth as you think is significant.You can show your judgment of the evaluation (who stands better and by how much – you don’t always have to say why) with any number of methods:
- Traditional: =, ±, ∞, …
- Computer - In pawns; negative means Black is better: +0.3, -1.2, …
- English: White is a little better, Black has compensation for his lost pawn, etc.