I did not buy replacement coils for my Arctic for almost 3 weeks after getting it, though I should have replaced it at about 2 weeks. I also use thick juices often; very dark liquids or very sweet seem to be more of the enemy, here. A tip for gettin gunk off, I pull on a q-tip and narrow it until it fits into the coil (I use 0.5 dual coils), twist clockwise until it stops going in, then reverse out, gets a Lot of gunk out. I use dry q-tips.
As for replacing cottom and dry burning, that would be nearly impossible with these vertical coils.
Another important factor is wattage, my cotton began to get very dark only when I began vaping more often above 40 watts. I didnt taste dry hits but i think the cotton was getting too hot. Same for gunk on the coil, it burned faster and got harder to clean off. If your coils are going bad that fast I can only suggest lighter juices and lower wattage