kayfun 3.1 = 1 tank before i change. i use a sweet, dark-ish juice in there and even a max fill is too much. just above the chimney and its just stating to get gnarly toward the end.
my smok octopus has an extremely dark juice in there and it can only handle 1ml or so before the coil gunk and gnarly wick rears its ugly head.
my trident is a beast. i use a next-to-clear juice in that one and i can put many many ml through it before it shows signs of lessening performance. maybe around 15-20ml id say.
my i-go coiled with 24g nichrome tends to burn the wick if i dont keep er nice n juicy. the wire retains so much heat that it will continue to vaporize juice for a few seconds after firing. often i have to suck in extra air or blow on the coil to cool it lol.