I only vape unflavored 60PG/40VG 9 mg/ml on an RTA at 10 Watts and my coil comes out to .5Ω with SS316L. I don't really keep track as to how long my coils last between wicking. Since it is not flavored, I re-wick when I get a slightly burnt taste or I just don't get the throat hit I am accustomed to. When I replace the wick, I pulse the coil and use a small wire Bristle brush to get whatever the gunk is off the coil. When it is at an even glow I add the cotton. As far as replacing the coil itself, I don't have a clue how long they last. If the wick's life is measured in weeks the coil is measured in months. I hope this is helpful in some way.