Hunter like everything it depends on luck. Some got commands in 12 months of arriving some years ago. Others arriving several years later had to wait 7 yrs on one fleet while it was 3yrs on the other. All of this is beyond the individuals control . I know some that have the majority of their provident fund in cash and bonds, and they will be working to the age limit to fund retirement. Others did well with property here and retired at 50 . Others lost all savings on property deals that went wrong .
For some, depending on when they joined, it could be mid late 50s. For others it will be later . Of note, those over 17yrs in will more than likely stay here and leave when they have enough to retire. Those with less time leave to work elsewhere. Well seems that way with the fellas I know anyway . In my time here my seniority has moved about 300 numbers, when those that joined a decade later have moved 2.5 times that. Not sure that will continue though as conditions seem to slide rather than continue.
But not paying income tax is a very positive thing when it comes to investing. Some countries will tax you when you send that lump sum home. Others luckily don't.