Common sense is when the light goes through the slot it will be 5volts on the line or 1 in digital.
In the code there is high res counter that goes to 720, so one slot[no matter full or empty] should represent 1 degree. Or the PCM can count the raising and falling edges of the slot and you got 2 degrees from one slot. Low resolution is used for trigger when the high res counter to start. The leading edges of low res is used to calculate the time the engine rotate 90* and from there it calculates the rpm.
I think low res is used for rpm calculations based on time and as a trigger for cyl identification based on high res counts between falling and raising edges of the low res slots.

High res is used for precise spark timing and sequencial injectors firing. A scope test confirmed that only the first 4 pulses at cranking are not sequential. After that is full blown sequential injection. The great starting times of the lt1 engine is based on ultra precise spark delivery at all conditions, and that is possible of the 720 degree opti wheel. No spark scatering at all since it is not time based but a degree based ignition.