I guess I’m lucky that I’m a mtl vapor because my cotton bacon prime lasts more than a week and still looks clean but I don’t vape above 40 watts so probably has a lot to do with it
For about a year I have been vaping on a series mech at .25 ohms with a pair of Samsung 20S batteries so, when my batteries are full, this translates to ~229 watts, or, on average, 5× the power that you mention. Yet, despite this, Cotton Bacon 2.0 lasts more than
two weeks for how I vape and still looks spotless also. My coils definitely don't give me a pitch black crust, very much unlike what's shown in the pic that was posted in the OP. Instead, I get just a thin, dark brown, kind of patina-ish layer that looks evenly spread along the entire length of the coils. But that's just because I vape only high VG premium juices the vast majority of which have quite a lot of sucralose sweetener in them─very often also they are custards/desserts/bakey type stuff that's usually a bit darker in color compared to your average fruity flavored juice.
Vaping on a single battery mech at .11 ohms on a Samsung 30T battery─100 watts lower than those ~229 watts that I was talking about─the Cotton Bacon 2.0 lasts almost a whole week
less long. There's nothing magical about that, as the coil surface temperature is still pretty much identical for both of these two different styles of vaping, or at least that's how I do my vaping─as I
don't let my coils overheat in any way whatsoever─BUT... the lower powered of the two is taking longer hits. So, the part of the juice that is located on the inside of the coils keeps boiling the cotton fibers to mush for a comparatively longer period of time during each hit. Whereas faster vapor production resulting from higher power─that's in cohort with stronger airflow slamming right into the coils as a result from precision tweaking─causes the juice to keep getting sucked out of the wicks at a faster rate
during the hit, which also helps to carry the heat away from the cotton on the inside of the coils. (The juice flow does.)
Coil construction also plays a part. Some of coil types, especially if using reasonably thin wire strands, can suck juice out of the cotton so much faster than the "simpler" types can, that a dual coil build that is still nowhere nearly oversized for your average dual coil 25mm RDA can still be capable to produce the kind of vape that does
not get hot... despite pushing a fuck ton of power through it.