This highly depends on where the npc is located. If they happen to not be at an aetheryte it could take a while to get to the location. You can purchase housing at lvl 50 before you reach HW. This means the npcs would have to be in no fly zones in ARR content.
Sure you could decide that the npc is always near an aetheryte but the coordinates aren't so precise that only one npc could possibly be standing in that location. Npcs are often clustered together. You can move a step between two npcs and the coordinates on your map won't change. I suppose SE could then decide to choose a named npc with no one else near them.
But none of this really matters because bots could very easily be coded to do this given they can do entire questlines and gathering across multiple zones on their own. Bots are already equipped with the ability to search for and get to coordinates.