No Fire!

You need to post what you have for an ignition, points, Mopar ECU, GM Hei, MSD, what???

The "open back" on a coil resistor does not mean cheap. Some were made that way.

They DO get hot, that is why they are made of ceramic.

If they are failing often, you may have a bad coil, or a mismatch between coil and ballast, IE coil is too low resistance, and is drawing too much current.

It also may be -- you are NOT I dearly hope-- leaving the key in the "run" position (as to listen to the radio) with the engine off?