Hi Vanjo.
I am essentially a strict carto tank user. I use atomizers to test a new flavor and from there, either it fails or it ends up in a tank.
That being said, when I first starting started using cartomizers, no tanks involved, I got about three fills (on an average sized carto holding about 1.5ml of e-liquid) before they started to taste a bit bland. I am all about intense flavor so I honestly never use a carto until it dies, just until I start tasting filler. And I'm pretty big on low maintenance vaping, so I don't bother with all the cleaning nonsense.
Since a good tank with a decently punched carto will keep the carto consistently filled, I get, on average, four tank fills with a 3-5ml tank before I don't get a full-bodied taste anymore. That's up to 20ml through one carto! And I commonly buy my cartos in bulk through Vapor Kings, so not only is it a stress-free way to vape, but it's relatively easy on the wallet.
As for when a carto goes "bad", I typically get a bit of a bland taste on the last tank fill, and then junk the carto after I vape through it. If you find yourself in a "gotta change that carto now" situation, you can pop off your top cap on your tank and pour the juice into an extra bottle (I keep several on hand) or even back into the original bottle if it's just one flavor. You will lose the minute amount of juice in the carto, but the tanked juice is easily salvageable as it has not been vaped. No weird tastes whatsoever in my experience.
If you have any other questions, feel free to shoot me a PM. I can help you out with everything from filling/refilling to some good starter tanks. Vape happy!
