I remember reading a LONG time ago from chev or a hot rod mag that if coil is wired back'''erds
that the spark does not jump correctly, ie it jumps FROM the ground electrode to the center of the plug and goes back into the coil, thereby greatly reducing the life of the coil.
if coil wired correclty then the JOLT comes from the coil and goes thru the plug center electrode and onto the ground electrode of the plug and then giving the normal life expectancy of the system. a simple test was given use a regullar wooden pencil and put a wire onto anothe plug (grounded of course) and insert the lead into the plug gap (yea hard ain't it)and if the spark starts on the ground side you are wired backard.