How many ml per day do you think you run
through them? I find mine give out after about 20-25 mls on the taste side. I could go longer if draw was the only concern.
The one I'm using right now has only went
through about 15ml and still going. The first one that I used went through 20ml before my decided to dissect it due to diminished flavor like you have stated. Since you have already used for about 20-25ml. I find that your carto has pretty much been used to it's capacity since a lot of other carto's I've used usually don't even last that long. And that's after cleaning it every 5-10ml. Although, I've found some cartos can only go for 15ml before it died on me such as the 1.5 ohm Smoketech Dual
coils (which I really hate for multiple reasons).
A lot of people might disagree with that fact and continue to clean/use them until they give out. Which one of the tips that most people give to others is to clean your carto at the first indication of a flavor change in order to prolong the life of it. Some say that they can run somewhere close to 50ml or more using that method. But, you have to be lucky to get to that point IMO. Most cartos will never even get close to lasting that long. I also find that after the first initial fill. Cartos do not give the same flavor as they did fresh, ever again. Especially after cleaning since I find that the taste diminishes or carries the remnants of the flavor I was using before, even though it's faint it's still noticeable.
Which is why I gave up on cleaning them due to what I just described. Plus, it's a hassle that I don't wanna deal with and so, I just throw them in the trash or dissect them to see the results of what happened with prolonged use.