Any coil you can rewick can extend its life for months, I won't even consider buying a tank unless the coils are at least re-wickable lol.. I started rewicking then rebuilding STM OCC coils and have been using the same ones since august, I still actually use the same ones that came with my STMOh yeah, 2 to 3 weeks.
And they are super easy to "re-wick"
Look on Youtube, many vids to show you how to do it.