How do you Change Nationalities?

[Shadowood]

Besides a select few players that run through nation missions really fast and hop nations just because (Shadowood),

I can neither confirm nor deny running through nations “really fast”.

I have heard it’s just a waste of resources. But getting your passport stamped is always cool!

[Captain Jack]

I don't see any exploit.

As long as no promotion mission is active, you can create as many nation change missions as you like.
If you have an active promotion mission, you must cancel it before taking a nation change mission.
At least 3 days must pass since the promotion mission started to cancel.
If you have an active nations change mission, you cannot take a promotion mission.

All the above have been just tested and they work in the way I described.

For reference, the only reason we got the cancel time limit is to prevent continuous farming of mission NPCs which normally are richer than the patrol npcs.