Using the Swap blaster trick to move flight masters (I used my garrison one) means you can start a flight path in any location.
What happens is when you take a path from the new location the mount moves through the ground and walls to get to the path.
If you have the time and patience to move your flight npc to somewhere crazy this could be useful fo seeing certain areas.
Edit: It seems that some flight npcs run back to their mounts, however the garrison one does not.