You pointed out a majorly important point. When I set different way point speeds, I keep an eye on total mission time. I try not to exceed 15 mins. to allow for "Crap, I ddn't see that coming" moments.What you sometimes need to be concerned about is that if you set a slow speed between waypoints and the AC looses connection the whole mission will continue but at the slow speed. It may mean the AC does not have enough battery to make it home.