I'm a recreational player, betting green to low black at 2D. For a three-four day trip to LV, anticipating 10-15 hours of play, I bring 180 units which is 20+ max bets. I usually walk around with 40 units, but I buy in small (10-12 units) and dig if I have to.
I keep my sessions to 45-75 minutes, and my spread to 1-8, to keep from giving the pit a reason to back me off. However, I try to maximize hands/hr by playing head's up or with no more than one other player, which means I play during uncrowded times, and during those periods the pit seems to have the time to watch.
I never leave on a win, e.g., just because I've hit 2xEV. I leave when conditions deteriorate. I leave if mentally I'm stressed or not sharp, the cut/penetration deteriorates, I 've been there long enough to give the pit enough data points to cause concern, or more players enter thus reducing hands/hr. It's all one long session, so if conditions are good, you should stay. You could win more than 2xEV and it will balance those times you lose 2xEV.