I have seen Italy make believe he wasn't in the game in S01 just to take Trieste in A01.

How do you know it's fake/pretend? And not accidently missed a turn?

As a strategy, I would strongly question it's value.

is that legit Mapu? like is that really appropriate?

Why wouldn't it be appropriate? Even in a "real" board game a player can not submit and order and game proceeds. Even in a real war and army can sit idle without orders.

I have occasionally manipulated the clock on a non-live game, where I check in three minutes before it processes on purpose to either put my moves in at the last minute assuming my opponents will think there will be no moves, or to do the opposite (adjust my orders if it looks like someone's not going to be there). Totally kosher either way, and I've done it in face to face before.

Of course it's legit.
As long as you do not curse other player when your ally stab you in the back because thinking that you are inactive or delaying the game purposely.

This was discussed elsewhere brainbomb, and you are correct in that it's kind of a cheezy tactic. It's not bad enough to be considered cheating, but it's sort of the last refuges of noobs and lamers who think they are really sneaky when of course no one could ever get away with this in a live game.

If you ever want to make a private game where this sort of behavior is prohibited, you could of course count on my participation. Private games are the solution to reducing these sorts of shenanigans.

Thank you Al. that would be fun.

If your goal is to alienate yourself from those around you via lack of communication and totally screw yourself, then I'd say you've hit pay dirt. When a country goes into CD, assuming it continues on, players jump on the free centers. Not a place I'd want to be intentionally.