Dormouse is def right. DOnt test juices with cartomizers, you could end up wasting alot. I keep a few attys around for testing juices and once I know I like one, I fill a cartomizer.
I dont know what PV you have, but if its a 3.7V I recommend you try the Ressurector cartomizers. They are awesome and produce huge amounts of vapor and great flavor. They are 1.7ohm LR and hold 2ml of juice so they last all day.
While cartos are meant to be disposible, if you fill them right you can get a lot of use out of them. Ive been using the same Ressurector with one juice for about 4 and a half weeks.
I HIGHLY recommend you use a syringe to fill your cartos. It is quick, easy, and ensures they are filled properly. Plus you dont have to wait for the juice to settle like you have to do when you drip into the top. They can be used right away
To answer your question, a carto normally gets clogged up before it dies, but sometimes the coil will break sooner. If you take care of them and fill them right then it should be that they clog first. I have never had a coil break, I normally retire a carto after its fairly clogged up.
For dripping and testing juices I use a HH.357 hybrid atomizer. Its expensive, at $22 but gives better flavor than any atty ive ever tried and crazy amounts of vapor. While it is expensive, If you take care of it properly you can easily get your moneys worth for it. Ive had mine for a few months and it still works great. My one buddy has been using his HH.357 for over 10months, so the $22 can def be justified