- Even good tacticians blunder
Even if we study tons of tactical puzzles.. there is no one telling us at a real game: psst, look for a tactical stroke now. We need to look for tactics at every move. So we need to create/follow/use a thinking process, which make us really look for tactics: Its necessary to analyse our opponents move: is it a blunder? Or is it dangerous, might we blunder? And if we chose a move we still might have to do an additional blunder check
- Puzzles are "clear" but OTB is usually fuzzy.
A positional puzzle is usually showing a more or less "clean" pattern. Either the puzzle is about mate or open lines or weak squares... but what should we do if several different things are to consider. What is better? To keep the pawn structure clean or to get a knight on a nice forepost or to controll the h-file? This type of "fuzzy" situation is most common OTB.
Houdini "told me", that i am to scared about my pawn structure, i play to seldom pawn moves. To find the right weights to the positional factors we need the right feedback. There are no puzzles where you have to decide BETWEEN different possibility's.
- Mental strength
You need to give all you have, if the opponent is weaker or if he is stronger than we are. Something you cant learn by solving puzzles either
We need to find our weaknesses OTB ( by playing a lot OTB ) and find a thinking process to "compensate" these weaknesses we find.