I've gone through 2 boxes + 1 coil (so 11 coils) of the prebuild stm ni200 occ coils. Out of the 11, almost all of them start off with a weird taste for the first 1ml or so. 5 or so have lasted about 1-2 days before a significant drop off of flavor and clouds (I am not a cloud chaser, I only use it as a measure of performance). I've had 2 coils last longer than 4 days, and of those 2 one lasted 3 weeks (seriously, it was a monster coil, and I could have used it longer but I decided to dump it because heck it was 3 weeks with at least 180ish ml's). I think just as its harder for us vapers to make ni200 builds, its harder for them to manufacturer them. Don't get me wrong, I've also seen a wide variety of quality in the standard occ coils (not the new vert) as well. But on average I get 3-5 days out of them (about 6-10ml's a day)