okay, here's the thing... there is no must fire at wattage for any given RDA/RBA/RTA I have run at ranges between 13w and 60w, it is all dependent on how it tastes... for a .5ohm coil on a new addy I would probably start out at 20w and work my way up till I hit the temperature and flavor I liked, that may be right at the 20w spot, or it might be as high as 60w, although for me personally I never fire a .5 higher then 30w, but that is my taste preference which is exactly what I guess I am trying to say... forget what anyone else is doing and enjoy your vaping the way you want.