If you can manage emotion beating or "timing" the market is not difficult given the all of the data we have access to. We let our attachment to ideas get the best of us far too often. Just today I had a couple of positions start going south sooner than anticipated. My system said sell but I was trying to convince myself they would reverse. When it was all said and done I plugged my nose and sold and entered another position. Saved myself from a 4% loss.