The Turtle Rules will work over a long enough period of time as long as you have deep enough pockets and strong enough will to withstand the false signals and draw-down these generate. The draw-downs are so significant with this method because a new entry is made on a new high signalled by a (Donchian-style) break-out: a new short is opened on a new low from a break-down. The odds certainly favour a continuation of either move in the direction of the break: however, because entry has been made at an extreme, if a signal failure occurs, the distance price might travel is that much greater. So eventual success as a Turtle has to be balanced with a significant risk of being wiped out.
In principle I agree with following strong trends but I think its smarter to find a pull-back in the trend so that you can buy in at a discount, and identify a tighter stop in case the signal fails. After all, if, say, Barclays, is rising steadily, then makes a new high and breaks out with a 10% rise in a single session, who would feel the best possible strategy is to buy BARC at the absolute highest price?