I was never a chain smoker unless drinking, but I was like a clock.  Needing one every hour just before the hour at about a pack a day.  (I don't sleep much) Anyway, I felt like a chain vaper, because I always seemed to be abusing my equipment (stock 901 auto).  I read a neat pdf document from this site under caring for a 510 or something of that nature.  The interesting thing I never considered was to have two or maybe more in your case at hand.  It said something like:
 
Only take 3-5 long drags at one time and then let it rest for 3 mins.
 
So it did seem that to satisfy my timely craving I would hit it fine a number of times, then struggle to produce the vapor or nicotene I needed.  This would lead to frustration and battery changing and over juicing and dripping etc.  What I really needed was another e-cig with me to puff on right after 4 or so good puffs from the first.  I would be good at that point or go back to the first one.
 
Maybe they could make a mod to keep the e cig hands free all together, like I would do while typing at my computer until the smoke got into my eyes.
 
hope that helps