Umm, what kind of atomizer you talking about? My rba's will probably last a lifetime, will probably have to change out the O-rings at some point, and maybe the coil mounting screws, and of course the periodic re-wicking and wrapping and new coil, but that's just pennies to do.
I assume you are talking about disposable atty's. That depends on the
juice you are vapping, the amount you vape, and any maintenance that you perform. Such as rinsing of
tank, cleaning of coils.... Maintained, weeks to a month. Don't really know, upgraded to a bcc then a few rba's before my cheapo clearos gave out.
I could get 3 weeks out of a pt coil head before needed to be cleaned or replaced. Rinsing out your tank every other fill helps too.