Why would it matter prebuilt or built yourself...if you check it before attaching on an ohmmeter and it says .5 or .6 or whatever why would that matter.....5 is .5 no matter if it's prebuilt or made yourself.
Because prebuilt coils are cheaply made with thin rubber insulators.
Some arrive dead shorted in the pack.
The Smoke TFV4 is built for high powered regulated devices. The coils are designed to be used with regulated mods.
Do you know exactly what to do when your battery starts to vent?
If not, you shouldn't be using a mechanical mod.