Some ejuices render coils useless faster than others, this isnt a new thing and i have experienced it myself multiple times. Pure pg wont, pg with dmt does it quite fast it seems.

Depends what the flavoring is made from and i dont know the specifics but what your talking about will happen with a dmt mix in a tank everytime. Drip style attys wont have that issue and are much cheaper to replace the coil with.