I usually pulse dry burn my ccells after the third tank. It seems like they are lasting longer or maybe I'm just fooling myself.
I've used a few dozen of the cCells, and:
First, I hope that you aren't dry firing the TC ones. If you are: STOP, and never do it again!
Second, I tried various approach to expending their lives and learned 1) the liquid is the #1 reason that kills a coil, the sweeteners will gum both the ceramic and the coil...and 2) I tried cleaning them every possible way I could think off, overnight soaks, using denture cleaner (as these are ceramic), alcohol baths, boiling them, etc. and I managed to get one or two to work (but not really all that great) for an extra 2-3 days at the most... in other words, it was NOT worth the trouble, once there's buildup in the cartridge, it's there for good, dry burning will only carbonize the gunk but still leave it stuck in the pores of the ceramic, and now you're inhaling carbonized gunk.
That said, I did find that the cCell are very easy to take apart and rebuild, and actually my rebuilds are a LOT better than the originals... with my diy (doing my own liquids without sweeteners), my rebuilds last me over a month easy. Between all the various compatible coils I have and tried and rebuilt, the Vaperasso cCell are the best shells, they are absolutely fantastic and the smartest design.
I just did a tutorial on rebuilding them if interested:
Vaperrasso cCell rebuilding