I think I got the answer I needed for my tanks. Seemed like I was running through cartos awfully fast...they would last about 2 days then start tasting burnt if using them in a 6ml. tank. I only recently started "embracing" the larger tanks (been using 3.5ml. ones awhile) when I started using mods almost exclusively. I couldn't figure out what was going on. What I was told was something that I guess was obvious, but no one told ME...and that was to take a sharp "dry hit" (without firing) every now and then to "prime" the carto in the tank. Especially helpful for chain vapers like me. I tend to vape so often and so hard I guess the juice can't wick into the carto fast enough! harhar!
Anyway, since finding that out...it's made a world of difference!! Much happier with the big tanks now!