Never run one dry. Constantly top it off. Natural juices such as primevaping will clog carto's faster and so will tastyvapor (I don't know why but it does). Some people will tell you sweet and dark juices will clog but I've never had any problems with either...only natural
juice vnedors that extract their bases from tobacco leaves. However, the higher the pg ratio and the lighter the color
juice, they will last a hair bit longer but they are cheap enough to replace. If you get a week out of one, that's awesome. I've used Boge 2.0ohm with DK-Tab (semi-dark juice) and have gotten 2 months out of a Boge before tossing it. It also depends on your
vaping habits. If you're a light vaper, you should get longer than a week based on the type of juice you use, whether it's low resistance or not, and the PV you are using it with. There really isn't a time frame for longevity...it depends on some factors, a few I already spoke of.