I know you are frustrated, but I promise you, it isn't the kayfun. Or if it is, you have a defective one.
Here's what I do.
I use 26g kanthal wire. I highly recommend 24g-28g. The thicker the wire, the EASIER it is to wrap coils. The thicker the wire, the less SPRINGY it is.
The kayfun performs BEST at 0.8 to 1.6 ohms. That is its SWEET SPOT. Any lower or higher, and IMO you aren't taking advantage of it properly, and performance will decrease.
What kind of cotton are you using? I ONLY use rolled sterile cotton from CVS. It was 7 bucks for a bag that will last me 5+ years. I tried the peaches n creme cotton yarn from walmart that so many people on here like, and it tasted terrible. The CVS sterile cotton is ALL I use, and I get NO taste from it, I only taste my delicious juice.
So, I suggest you use sterile, rolled cotton from CVS. Get 24g-28g wire, and use a 5/64" drill bit. Make sure all your wraps are touching each other ,and test it out on an ohm meter. I go for 0.8 to 1.2ohms.
If you do this properly, your coil should last a month no problem, and the cotton should last about 1-2 tanks before you notice a reduction in flavor.
Like I said, I understand your frustration, I really do - but I encourage you to keep trying, because in all honesty, the kayfuns is one of the best products on the market right now.
Also, I moved away from the micro coil in the Kayfun.. went back to a standard coil and more cotton. No more dry hits halfway through a tank using NETs.. in fact, my latest build, I am on the bottom of my third tank, using NETs...

