Man, I'm doing something wrong then... if I eek up much over 11W in my NEBOX, it burns after a few 5 second pulls. I usually keep at at 10.5W. Right now, the coil I have is about 3mm ID with 8-9 wraps (can't remember), the NEBOX says it's 1.15ohm and 3.45-3.5V when in use. I've enlarged the channels quite a bit and lessened the amount of cotton bacon wick I use, which seemed to help.
Maybe I should try a lower PG juice? I've been using Mech sauce 80/20 6mg Ape Frenzy for the past 6 months.
I use similar coils (couple more wraps per coil) in my Avocado dual coil on an Eleaf iStick 100W box. It says .78ohm, 4V and 21W.
In both devices with how I have them, I can go 4-5 days before the wick gets bad tasting. I dry burn the coils and hit them with cold water to clean them, then re-wick.
This is my avocado, don't have a recent photo of my nebox: