Hey Moody,
Cartos/atomizers could die at any moment, however they tend to last longer than stated by the manufacturer. If the cartos you're using are pre-filled with juice, then I'm not sure how long they will last you as I only use non-filled cartos/attys.
From my experience, I get around 1-2 weeks for a LR Carto at 3.4 volts (Ego) or 3.7 volts (Silver bullet) as long as I keep it wet, so that means dripping 3-4 drops every 10-20 puffs. For LR atomizers, I have been vaping steady since mid February and have yet to kill an atomizer, though I have about 5 in rotation due to different flavors. I use Boge cartos and Vaper Kings 510 LR atomizers. Both have performed admirably.
I also clean the batch of 5 every 3 weeks or so by running them through an ultra sonic cleaner with distilled water. This generally just cleans out the juice/flavor.
The quality of the atty/carto could be part of the reason for my specific experience, but I would tend to believe that with a little care, you should be able to get decent life out of any carto/atty.
In either case, you've come to the right place as ECF has all the information (and opinion) you could possibly need.
Welcome!
J