[NoDOHC]

Correct you are, but there is only one side that matters anyway (the other side is the 'wasted' spark) so a misfire is just that, a misfire.

The air has a very high resistance until the electric field intensity exceeds the breakdown level (based on plug gap, AFR, compression ratio, charging efficiency, boost, etc.) no appreciable current will flow until the air between the electrodes is ionized. Once this happens, the resistance drops to a very low level, effectively shorting the coils out (voltage drops very low) The actual spark is then a current through the now-ionized air gap.

The problem with parallel circuits is that the dielectric strength of the spent chamber (just completing the exhaust stroke) is a lot lower than that of the compressed chamber with air and fuel in it. This means that the spark voltage will build until the field intensity exceeds the breakdown level of the lower dielectric, then that ionized gas in the air gap of the spark plug will short-circuit the coil (spark voltage goes low) while current flows through the air gap. This means that the charged chamber will never get enough voltage to the spark plug to exceed the higher dielectric strength and the charged chamber will never fire.

Wasted spark is very reliable (typically). I don't like it because it requires twice the effort (ignition events) out of each coil (while it only requires half as many coils) the charge time for the coil is half as long as it would otherwise be, this means there is not enough charge time to get a reasonable ignition energy to the air/fuel charge in the chamber at high revs.