Here is some more testing with interesting results.
The first test is only entering on either a Friday or Monday (trade would close either Monday or Tuesday). By doing this the R squared increases, largest draw down is significantly lower, the volume of trades are reduced by 60% (60% lower overall commissions and fees), and the relative average daily gain remains the same.
The second test has the same parameters as the first but in addition it only trades overnight when the previous daytime session was down, and only if it was down by more than -0.5%. What it looks like to me, in my short time testing, is that performance is generally worse when the market goes up by any amount in the previous session, and also when the previous session didn't move much. The best performance slice of that pie is when the previous session is down by a decent amount.
Profit factor for these two tests are 1.51(second test) compared to 1.31(first test), so the overall bang for your buck increases when you add these thresholds, but it significantly reduces number of trading opportunities. 2500+ trades for the first test compared to 500 for the second test.
First Test
View attachment 201048 View attachment 201049
Second Test
View attachment 201050 View attachment 201051