...depends on the juice and the carto for me but, apparently, not very long compared to many folks.  Anywhere from 1 week down to two days (with one 4 hour aberration, noted below).  
I use 510 devices: a variety of ego/Kgo/T-Rex batteries (3.2 to 3.7 volts, I'm led to believe) and a Darwin, usually at 8.5 watts (voltage varies depending on the carto/atty, usually below 4, rarely over 5.2). I like low resistance cartos so I don't really need high voltage.
I'm a chain vaper but I've never had a cartomizer "pop" or stop firing. I keep them wet and never burn the filler anymore, either. (Learning curve, here.) I *always* give up on them before they electronically expire. They just tighten up until they're simply too hard to draw comfortably. Cleaning gets me one more day, tops. Half of them don't improve enough after cleaning and drying for me to consider refilling them.
For cartos, the amount and type of filler seems to be relevant:
Single-coil cartos (of any resistance) seem to stay unclogged longer than duals.
Opaque dual coils (black/steel) seem to last longer than clears (Possibly they have different filler material?).
Regular-sized/"Short" cartos last considerably longer than xl/xxl cartos.
Unfortunately, my favorite all-day juices are dark, VG-thick delicacies that have a (usually pronounced) sweet component.
AVE Boba's Bounty (praise The Force!) performs pretty well in spite of this. I'm ending my 4th day with a CCV 2.7ohm "resurrector" and the draw isn't even mildly annoying, yet.
On the other end of the spectrum, BwB's Casablanca (an absolutely excellent flavor, I will NOT give it up!
  gummed up a Boge 2.0ohm for me in less than 4 hours, last week.  Haven't cleaned that carto, yet, so I don't know if it will survive.
I've heard that diluting dark/sweet/vg-based juices with pg and/or grain alcohol will help alleviate this problem but I do not want to lose flavor, vapor production or nicotine content. If I ever run out of money and cartos at the same time, I guess I'll just drip.
	
		
			
		
		
	
			
			I use 510 devices: a variety of ego/Kgo/T-Rex batteries (3.2 to 3.7 volts, I'm led to believe) and a Darwin, usually at 8.5 watts (voltage varies depending on the carto/atty, usually below 4, rarely over 5.2). I like low resistance cartos so I don't really need high voltage.
I'm a chain vaper but I've never had a cartomizer "pop" or stop firing. I keep them wet and never burn the filler anymore, either. (Learning curve, here.) I *always* give up on them before they electronically expire. They just tighten up until they're simply too hard to draw comfortably. Cleaning gets me one more day, tops. Half of them don't improve enough after cleaning and drying for me to consider refilling them.
For cartos, the amount and type of filler seems to be relevant:
Single-coil cartos (of any resistance) seem to stay unclogged longer than duals.
Opaque dual coils (black/steel) seem to last longer than clears (Possibly they have different filler material?).
Regular-sized/"Short" cartos last considerably longer than xl/xxl cartos.
Unfortunately, my favorite all-day juices are dark, VG-thick delicacies that have a (usually pronounced) sweet component.
AVE Boba's Bounty (praise The Force!) performs pretty well in spite of this. I'm ending my 4th day with a CCV 2.7ohm "resurrector" and the draw isn't even mildly annoying, yet.
On the other end of the spectrum, BwB's Casablanca (an absolutely excellent flavor, I will NOT give it up!
I've heard that diluting dark/sweet/vg-based juices with pg and/or grain alcohol will help alleviate this problem but I do not want to lose flavor, vapor production or nicotine content. If I ever run out of money and cartos at the same time, I guess I'll just drip.