Seems like everyone is talking about CE4's today. IMO if you have 2 coming, I would get a couple more or better still order a couple of something else. I know how easy it is to lose one for some reason and then you would only have one with no backup.
I used to use CE4's or Vision Stardusts as my main vape for a while last year. I would typically get a few weeks from one and have gotten as much as 6 weeks a couple of times. I used to rinse and dry burn after every couple of tanks. The wicks are silica and the heat of a dry burn does not affect them. What does affect their life is if you let them get too gunked up. That's bad as they then become very hard to get clean. I did once buy a cheaper clearo and found the wick deteriorated after the first dry burn, so I always stuck with the Vision product after that.
Here is a video on
how to dry burn these. What he does is pretty much what I used to do and still do with my Vivi Nova coils. Don't worry about water on the wick, it will dry off in a minute once you put power on it. The trick is not to leave power on for too long or you will melt (people say 'pop') the coil. Watch the color of the coil. Once it gets red, immediately stop powering it. Of course, a gunked up coil makes for a pretty lousy vape, so you don't have much to lose if you destroy it. I poped one and then it never happened to me again.
With no maintenance, I estimate a CE4 will last about 2 to 5 tanks, depending on the juice and how much tolerance to deteriorating juice taste you have.