[DbPhoenix]

In my experience, it's both. If traders are trading the value range, the better moves are from the extremes toward the middle, particularly since they usually continue toward the opposite extreme.

However, if traders are working toward a new value range, as they did two days ago, the move can start at the midpoint of the then current range and take off to points unknown (that one caught me off guard).

The best advice I've received so far is to plan your trading according to where you open in relation to the then current (volume) range (what you might call the +/-1SD range). If you open within that range, look to trade the extremes. If you open outside the range, look to the range to provide support or resistance, depending on where you are in relation to it. If you open within the range and try to trade one extreme or the other but break out instead, you have a real challenge facing you. Entering these breakouts is tricky, to say the least.