For price to head from point A to B, it has to travel at one point or another instead of staying stagnant. So if price can only move during a trading session, the session is segregated to test, and range expansion. With range expansion, limits are broken. If volatility is low, most instances the range expansion is attributed to news events. The test is usually at a outlier. https://en.wikipedia.org/wiki/Outlier "In statistics, an outlier is an observation point that is distant from other observations. " Most temporal fleeting outliers occur at points contrary to predominant trend.