Remember that this type of filter is only good for the setting you put it as, as long as you fly a straight track along the point A to B you set the filter for. If you turn several degrees while you are filming, the whole setting of that VND will change completely. Just in the same way that you can't just fly around and film and expect the whole video to look the same, if you were using a CP filter, because the angle to the sun has a direct effect on how the scene will look when using a CP filter. Some people don't realize this and think it would be like a UV filter or something.
When on the ground and looking through either the VND or CP what looks best in one direction, as you turn the one against the other, will change quite a bit as you rotate your body to the direction of the sun, as you look through the filter. These are usually best for on the ground filming where, as you rotate around, you can access the front of your lens and adjust the filter for each new direction you may be filming.
You can't do that from a remote camera flying through the air. So you'd have to film in one direction then bring it back and check to see how it looks through the filter for the correct effect if you were flying in a new direction and then reset the filter and take off again and set up to just fly that direction and if you wanted to change direction again, land and do the whole thing over again.
In my mind, these type of filters are a waste of time unless you just want to film in a straight line between landing each time to reset the filter for the new intended straight line direction, to next film.