Cash, you might be on to something.
I put together some code for a trading system based on gap entry. Here are the rules:
1) Buy when opening price shows X % increase from the preceding session closing price AND price is greater than the value of the Y time constant exponential moving average.
2) Sell when the low price of a session is less than the value of the Y time constant exponential moving average.
3) Position size = ( heat * equity / 100 ) / (10 x average true range)
Testing the system with 22 years of stock price data for Ford Motor Company shows these results:
EMA Time Constant 300 300 300 300 300 300
% width of gap 0.5 1 2 3 4 5
Number trades 29 23 19 12 10 9
Profit after commission, slippage 253975 267255 265079 241892 228877 84007
Per cent annual growth rate 11.54 12.15 12.05 11.00 5.41 3.82
Per cent greatest drawdown 11.46 10.39 14.00 12.03 14.01 16.76
Attached is the output of one of the trading simulations.