Hello Tina, welcome to the forum.
I have the Smok Mag 270 with the Baby V2 tank. The Mag 270 is semi regulated, it has no wattage adjustment. Its limited to a maximum wattage of 70W.
The Baby V2 is a great tank as are both the S1 and S2 coils.
Because the mod fires like a mech mod, it does vape depending on the coil ur using and the charge on the battery.
In my experience, the battery does drain pretty quickly because of the high wattage its firing at. I have the ijoy battery and it lasts around 5hrs before needing charging. Molicel and Ssmung 21700 last a bit longer.
I prefer using the S2 coil and do get a good 2weeks out of it before it degrades.
Using the tank on a variable wattage mod at a lover wattage does improve the coil life. I run my baby V2 tank with the S2 coil on other mods at around 30W and the coils last ages.
While the Mag 270 is a good mod, it is limited by having no wattage adjustment so not ideal if you want to fine tune your vape. The Baby V2 tank and both the coils are very good, one of the best Smok make.
I wonder if your juice is causing the issue with your coils. Have you tried changing flavours to see if that helps.