I use Protanks, Evods, T3's, and T3S's pretty heavily. As crxess stated above all those variables play into account. With taking great care to do proper maintenance on Kanger bottom coil heads, a head should last close to a month each in my experience, no matter the liquid. Darker,thicker, and sweeter liquids, equals just that much more maintenance and are the biggest contributing factor next to user usage, ie length of draw (how long the coil is fired), and wattage/voltage (how much power is running through the coil). Out of all my liquids, the one that gives me the most maintenance as an example is Ms T's "Ms T(wink)'s Sponge Cake", high VG, dark liquid, creamy, cake type, and very sweet flavor. About 2/3s of a tank on a T3S, peak performance tapers off, second tank without cleaning, about 1/2 of the second tank barely get anything from the coil the wick is so clogged and coil so carbonized liquid isn't vaporizing. So with that flavor I rinse the head each refill, every 2nd or 3rd dry burn and rinse, end of the week like all my heads, into a 20 minute everclear soak, rinse, dry burn, rinse and dry cycle. I get 2 months in between my coil rebuilds or replacing them, as I also have 2x the number of tanks filled and in use, is that many heads I am using, 1/2 in the tanks, 1/2 cleaned and drying awaiting to be put into use, rotating these heads every rinsing/cleaning cycle.
Simple Rinse and clean your heads regularly, get on a schedule with them
Rotate heads in your use schedule
Every couple tanks an intermediate cleaning, rinse, dry burn, rinse again and dry
Every week, advanced cleaning, soak in everyclear or vokda about 20minutes, rinse out, dry burn, rinse and dry
Wick stays dark where the coil is touching, or are blackened and scorched after a dry burn, time to replace the wick, head, or rebuild the head.
