tarbat i agree but looking at your log you would still have picked the flight up twice even with a 15 minute interval. what about 30-45 min
Remember you're only seeing the END TIME in my log report. I'd expect the time interval to be between the END TIME and the next START TIME.
30-45 minutes could mean that an aircraft lands, and then takes off, and you'd only get one flight record in the log. Would only be a problem for aircraft without FlightIDs, because typically the FlightID would change between landing and takeoff.
I think anything more than the turnaround time could be a problem. As an experiment today, I've increased my TIMEOUT time in preferences to see what that does to the log.