The cables altitude will also drift day to day and even possibly hour to hour due to the weather since it's using the barometer. It's always good to slowly pre-fly the cable, especially if it's something you've saved previous and are coming back to. It may not be exactly the same. I try to leave at least 20 feet clearance in all axis, and that seems to be working pretty well. One cable changed by about 10' vertically when a storm was rolling in over several hours. The next day it was back to normal.