No you do not have to change it that often as long as you don't burn the cotton (in a tank). You don't have to change coils in an rda for awhile either
I mean I wouldn't mind a bit of hyperthyroidism, a little weight-loss XD. I use 3mg nic just so I don't blow through juice as fast, but I feel the nicotine may be the issue, because for some reason (maybe it's just me) I get hungry after using nicotine, even after a meal.