After trying a few different coils I am now in favour of effort vs reward on US cleaning stock coils, I don't know if it's the way they wick them but 2 of my Smok coils have lasted longer than from new, I suspect the cleaning process has perhaps loosened the cotton a little, though I cannot visually see any difference between reclaimed and new.
My Vapbus coils are lasting ridiculously long, had 1 in over 3 weeks now and no signs of it dropping off flavour, but to be fair I tend to use thinner juices in that tank and vape less (still a few times a day).
I think I did mention before, you do need a few long cycles and I reluctantly ended up having to add a couple of drops of washing up liquid, follow by 2 more pure water cycles to clear the washing up liquid (if that made sense).
You know when you are getting somewhere when you see gunk forming or dirty water, I saw nothing on the first 3 cycles.