1...........What are you buying for coils? Brand? Exact part number?
2...........What are you running for an ignition, IE points? Mopar ECU? Other?
3...........Ballast resistor?
4...........Have you done anything towards voltage measurements on the coil and resistor, and system running voltage at the battery? Any trouble with the battery boiling over?
5..........Have you checked for coil heating, IE run it awhile and felt the coil?
6...........Do you or anyone routinely leave the key in the "run" position with the engine "not" running?
These, and many other questions.........................
To put things in perspective.............I've junked out a couple of cars, one was a 77 Dodge van, and I do not believe the regulator, the ECU or the coil have ever been replaced. I would bet money that the ballast had not, either. In my lifetime, on my own cars, I bet I've only needed to replace a couple of coils. (I'm 65 years old) I have had to replace a couple of ECUs and a couple of ballast resistors or maybe more. At least one or two ballasts may have been damaged by cold (winter) splash.