The Turtle philosophy seems to be based only on buying new highs and selling new lows, as a follow-up to the Donchian System for mechanical trading. I also notice they don't mention central tendency and volatility expansion/contraction cycles in their website, which seems to be more popular among discretionary traders. In short, they claim that their method is the only one compatible with trend following. Everything else, including profit targets or working with risk/reward ratios, is supposed to be prediction and, therefore, a fundamental error. What do you think about that?