I am vaping mallow mint or candy cane in it.
Only sub ohm vapors could go through 60ml in three days (watching it all go up in a cloud)
I regularly will vape 60+ ml through a carto, and sometimes I have tossed a carto for no other reason than I'm sick of looking at the damn thing.
A simple trick for longevity is clear liquids go in a carto, and dark liquids go in an atty that can be washed.
I've had the same experience. When I first bought my IBTanked glass carto tank, I used it with the original carto that came with it (Smok brand) for three months and never noticed any change in flavor or performance. Granted, it took me well over 2 weeks to go through a tank, but that is still phenomenal longevity. (FYI I was vaping a clear menthol juice in it.)
The only warning I can offer is that if you continue to use the carto past that three month mark, you'll eventually start to notice a flavor change and it will taint the entire tank of juice sitting around the carto as well. Because of this, I now switch out my cartos at about two months even though it doesn't seem like it needs it.
HEck I have one CE5 that I have never changed the head on and only dry burned twice in 5 months.
Stuffing probably made of fur from shaved Duracell bunnies.
The mint might be freshening it up?