I vape NET (notoriously gunky), so I dry burn/re-wick RDAs after 4-5 hours of constant use. For RTAs I dry burn/re-wick after every tankful which, for me, is about twice a day. I usually rebuild the coils every 4-5 days to maintain peak flavor. At $6 for 100' of Kanthal A1 and $12 for a bag of organic Japanese cotton pads it costs around $0.15 to coil and wick a Magma and about $0.05 to just re-wick. That's the beauty of RBAs, even using the highest quality supplies available it still costs only pennies to rebuild.