The basic idea which Frost along with Prechter propose is that stock markets peak have a cycle of 8-9-10 years, that is 1902 peak is followed by 1910, 1919 and then 1929. Similarly Troughs follow a cycle of 16-18-20 years and Major Troughs also follow a cycle of 16-18-20 years. When compared with actual data we see some incredible timing and some clear cut misses. The 1995 trough prediction surely is a major flop and 1975 trough prediction a stunning hit! Similarly 2000 high and 2003 low prediction makes you tend to believe this guy and 2009 low and 2007 high not getting predicted makes you throw this mumbo-jumbo out of the window! If we were to believe it 2010 should see a high which may or may not be higher than the one in 2000 and 2011 should see a trough which can be referred to till we reach 2018! The chart of Dow from 1900 can be found here.
Well Benner and Frost tried their best to find the golden timing technique which can give us the best time to buy and sell stocks. They used the known cyclic nature of economy to get to the unknown ways which govern the cyclic nature of stock markets. The basic problem which can be pointed out is that how Americans do business and what their economy runs on have changed a lot from what Benner observed and even after Frost and Prechter modified it. Still I feel we can put some faith on these guys and the years of research and hard work they have done to arrive at this. Who knows 2007 highs would be diminished by 2010's and 2008 lows will look better than 2011's!