In the post on when technical analysis works and when it doesn't, I proposed that markets move in and out of periods of stability. During stable periods, we have relative uniform participation in the market and those participants are doing relatively uniform things in terms of buying and selling. A technical analysis indicator that "works" during such a stable period will tend to continue working as long as that uniformity continues. Once we see a different level of participation (volume) in the market and/or once the distribution of buying and selling among participants shifts, then new patterns emerge. The technical patterns that had been reliable no longer are such going forward.

This alternation of stability and change occurs at all time frames for markets. It is a major reason why trading is so difficult, and why it is more difficult than many other performance domains. The football field does not occasionally change its dimensions; nor do the rules of football shift part way into a game. The equivalent of those things happens daily in financial markets.