I stopped having bias long ago, I can't test those. But I would have to say walking away is toughest thing to do as I now only trade ES first 30 minutes of the day session, so I suppose the last trade is the toughest trade for me. I have done so much backtesting though the years, I now only trade so many hours/minutes on various markets and walk away, no point in working like a zombie for 4-5 hours if the blunt of my profits come out of certain times. But it is rather cool to watch some markets ten minutes than sit there six hours.