the only problem with excessive tank size is the fluid stays in the tank so long that it is constantly getting heated on reheated by the atomizer post (heat has to go somewhere) and usually causes it to turn a yucky color, sometimes getting thicker and not wicking so well, possibly even changing or killing the flavor.. even 6 mil is alot of
juice for one shot. if you want to try and have one fill a day go for it, but I like the idea of a smaller tank (3to5) meaning each refill is fresh juice again.