Here is a backtest using Jim's bottom detector signals. From the signal out one full year the system holds QLD (NDX100 x 2). The rest of the time it holds SPY - the S&P 500. No signals are used to go to cash.

It loses to the S&P 500 LTBH in two years - 2021 and 2022. In both cases the difference is minor. It wins in all other years.

       Mungo    Index
Years  ROI      ROI
2009   173.08%  52.84%
2010   12.78%   12.78%
2011   2.58%    0.00%
2012   49.65%   13.41%
2013   32.31%   29.60%
2014   19.87%   11.39%
2015   16.94%   -0.73%
2016   14.23%   9.54%
2017   21.70%   19.42%
2018   2.81%    -6.24%
2019   80.88%   28.88%
2020   134.43%  16.26%
2021   25.11%   26.89%
2022   -28.59%  -19.44%
2023   89.09%   24.23%
2024   18.38%   17.32%

These are the actual trades. None of them see holding the index LTBH beating out the system by a significant amount!

Sig  Held  Entry Date  Exit Date   % G/L    SP500
     SPY   3/2/2009    3/4/2009    1.60%    1.72%
E    QLD   3/4/2009    3/4/2010    166.29%  57.53%
     SPY   3/4/2010    10/4/2011   3.16%    0.09%
E    QLD   10/4/2011   10/3/2012   71.35%   29.10%
     SPY   10/3/2012   9/25/2014   40.98%   35.49%
E    QLD   9/25/2014   9/25/2015   8.58%    -1.76%
     SPY   9/25/2015   9/30/2015   -0.63%   -0.59%
E    QLD   9/30/2015   1/20/2016   -2.74%   -3.16%
E    QLD   1/20/2016   9/29/2016   35.16%   15.69%
     SPY   9/29/2016   1/19/2017   5.85%    5.23%
     SPY   1/19/2017   12/24/2018  7.77%    3.86%
E    QLD   12/24/2018  12/24/2019  107.40%  37.10%
     SPY   12/24/2019  3/16/2020   -25.33%  -25.97%
E    QLD   3/16/2020   3/16/2021   223.71%  66.07%
     SPY   3/16/2021   9/29/2022   -6.06%   -8.13%
E    QLD   9/29/2022   9/29/2023   56.54%   17.79%
     SPY   9/29/2023   9/12/2024   32.15%   30.50%

Now it is certainly true that I've not found every single case where Jim has posted a signal. I may have missed some. This little test is simply to illustrate that it can be done and it is not all that difficult.