The coils on my protank are lasting me around 8-9 days before they start loosing flavor, then after a soak and a wash, another 4-5 days. After that, I've been tossing them in the emergency backup bin. I have recoiled one, just to see how hard it was, and it was rather simple. Took maybe 10-15 minutes on my first attempt. (Have never recoiled anything before, but decided I wanted to learn how to recoil Protank heads and EVOD heads) The only liquid I have run in my protank is MBV's Extreme Ice (3 flav shots, 50/50, 18mg) I run mine on my eVic at 8 watts which puts it near the 4.5v mark with no issues. I did switch to the 1.8 ohm heads when I ordered a new 5 pack, and I am on my first from that pack now. It read 2.3 ohms the first day, nor reads 2.1-2.2 ohm 3 days into it. QC may not be the highest on the coils.
Whats happening with your coils? Are they loosing taste, or actually failing? What kind of liquid are you using? I imagine using something heavier than what I am using could make the heads go bad faster. When ever I get my next protank in (a few weeks away probably), I will be loading it up with different heavy flavors (Cinnamon Roll and Pineapple Upsidedown will be in the 2 protanks that I have coming from a co-op)