During my HT tour, we had an officer jump on a grenade for an IA to a UN Peacekeeping Mission in Africa (blue helmet and everything, she had to go through Army courses for shooting, driving, etc.), but the deal she made with the detailer was "this time doesn't count against my shore tour," and made sure our CO and CDRE were well aware of that deal.
Fast forward to her return from Africa and surprise, surprise, gets the email from the detailer telling her she's up for her disassociated tour. "Not so fast, you made this promise."
"Sorry, that was my predecessor, pick a coast and type of boat."
A few emails from CO and higher ups fixed that relatively quickly and she did a lat txfer to the USCG and is still flying.
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FWIW, all of my experiences with PERS except one have been positive, and ironically, the only "bad" detailer I had was for my initial shore duty orders. With that said, I guess I've kind of accepted how the game gets played (cutting shore duty early, making boat tours last as long as possible), and never fought it, but I feel like the rest have been honest brokers with me.
On my current joint tour, I am going to ask to extend about three months so that my kids can, for the first time ever, finish a school year at the same school, but I know that will be a mega fight since they will want to pull me for O-5 sea duty if I don't make command.