The semiconductor ignitions are mainly restricted by "average current" not really by surge current that may be controlled by "coil resistance" but actually is "inductance". Inductance can moderate surge current.
Most folks don't understand the difference between resistance, which describes steady state current flow without time as a consideration. Inductance is a for measuring an inductors current and is AC in nature as DI/DT of (I) current over (T) time.
Most transistor peak current rating is over double the average current rating. Average current is it's normal running limit. The RITA could run 10 amps surge but only desired 5 amps continuous.
For example I repaired a RITA that ran a 1 ohm coil for almost 15 years. (12-14v) divided by 1ohm = 12-14 amps. A rita is 98% duty cycle(time) so it was running 11.76-13.72 amps. The unit was using over 100wats of power. An old boyer at 75% duty cycle would probably die much quicker as the plastic and potting would retain the heat and the RITA transistor would shed heat to the aluminum housing heat sink.
To add to the physics problem is that most newer transistors are of a smaller size and are not as thermally resistant to these abusive heat/temperature conditions.
HEAT IS THE KILLER
Heat at the semiconductor junction will eventually destroy it's doped silicon layers. At first not working very well and finally unable to control the electricity as it death spirals from self heating.and if enough current is able to burn it open, otherwise it stays nonfunctional electrically shorted forever.
No switching on/off causes no sparks
Using coils with higher resistance(inductance) will certainly help the ignition maintain a healthy average current level and reduce the heat/temperature condition.
Intelligent ignition mounting to enhance cooling is also highly desirable.
