I have never tried the echo cartomisers myself, but cartomisers themselves, by design will only last a few days to a week for a heavy vaper like yourself. I get 3-4 days from mine before performance starts to diminish. I would anticipate this cycle, regardless of liquid capacity the cartos have. Even the dual coil 5 ml cartos seem to diminish just as quickly as others.
You will quickly find that all parts have their pros and cons. Attomisers have a lifespan, as do carto's or
tanks. You'll find your swing of things based on your personal use of them. This can also be tweeked by variences in liquid flavor, or formula, to increase
throat hit/ satisfaction.
Overall, just be open to trying new things, and get going. You'll find what works best for you, and if ya sniff around, you'll find a review for just about anything made for e cigs on this forum. Its a learning curve, but with e cigs, its not so much about the destination-(though its nice when you find your perfect
vape), but more about the journey and all the available options out there.
** yes, carto capacity lowers after every fill it seems...eventually, you'll put the same amount of liquid you always have before in them, and they will start leaking because they no longer hold that much.
Dont waste time trying to tear them apart or clean them. Its not worth the hassle. They are disposable, meant for one or 2 uses, though you get more. Boiling them is an even bigger waste of time. Disregard all attempts of "cleaning" cartos**