There are three chess posts sitting in my RSS reader that I have saved for several months. I saved them because I really like them. What's interesting is that they were each written in different years (2007, 2008, 2009), they are all related and they pretty much have the same point ... looking deep into a position is futile; so don't do it.
First post: December 13, 2007 - "How Deep Do You Look" by wormwood
Second post: May 7, 2008 - "Multiple Choice" by drunknknite
Third post: October 8, 2009 - "A Word on Planning" by Nigel Davies
Here are three quotes from each post respectively:
"The errors happen 1-2 move deep, and the overwhelmingly most common one is underestimating a move that you did look into. And by underestimating I mean direct consequences that are blindingly obvious once you see that move made, not consequences that lie deeper." - wormwood
"The truth is that when we understand the position we see clearly, we do not overlook things, we do not make mistakes. It is when the position is beyond our comprehension that mistakes become easy. It is no longer easy to distinguish between moves. There is no way for us to tell how to proceed because our knowledge of this particular imbalance is limited." - drunknknite
"I have been thinking a lot about planning of late, especially with regard to its connection with intuition and minimalism. ... The more elaborate a plan, the more there is to go wrong at every stage of its realisation. And this is without considering the role of the opposition, whose goal is not just to refute various plans but to lie in wait for the obvious ones, constructing his game to meet them most effectively. So should one actually have a ‘plan’ as such, or is the entire concept flawed? I’d say it needs some adjustment in that a ‘plan’ must have enough inherent flexibility to change at any moment. And what characterises the game of strong players is the way that their moves often seem ‘multi-purpose’, fulfilling a role in multiple potential plans." - Nigel Davies
My oversimplified suggestion (and by no means is this an expert or professional opinion) is that plans should be discouraged (thinking beyond 2 ply) and that time should be spent trying to understand the current position on the board and then finding the best move that improves your position.
Now cue the sarcastic comments, "wow. brilliant suggestion Einstein" or "tell me something I don't already know."
Anway, go read those three posts. They are worth the time and effort.