Isolating the curves for the symbols I traded most CL, NQ, ZS yields this look:
Finally, a few more charts looking at all trades:
That last chart seems to show fairly clearly that trades I exit more quickly tend to be losers and trades held longer (6+ min.) tend to win more often. The conclusion in past years has been similar. I think this is best explained because the longer you hold a trade, the more likely you are to overcome the spread (or make it negligible) because price has time to move away from your entry. A trade held for 0 seconds, the extreme example, means you bought at bid and instantly sold at ask, or vice versa. A 1 tick loser no matter what!
Needless to say, I am still searching for a methodology and system(s) that have a consistent edge that I can trade. Perhaps 2013 will be the year! Onward we go...