OW Explorer: Do entry and exit flights count against segment limit?
 

If I am allowed 4 segments in Asia, does my flight from LHR-HKG count as one and my flight from HKG-LAX count as another, so that I only have net 2?

Arriving and departing flights to/from continents do not count toward the segment count.

You still have 4.

No. I did something similar recently. The 4 segments are only the segments within the continent. The segments into or out of the continent do count towards the 4 seg rule.

Keep in mind that if you were to do something like SIN-HKG-SYD, connecting in HKG on your way to SYD, the SIN-HKG segment would count towards one of the 4 segments within Asia even though it is being used only to connect to a segment that leaves Asia.