Mine is calculated this way:
Q: May I have a few days off?
A: Yes, now's the time
A few hours into my "time off": Hey, you need to come in now! XYZ is broken, and the boss needs blah, blah, blah, and we need to move aircraft A to location B, before the boss comes back early (tomorrow) .
And by the way Cujet, it's only been 7 years without a raise or bonus, you need to wait till next year.
Note: Our agreement was 10% bonus per year for staying, and annual cost of living increases. While I can complain plenty about the utter lack of vacation, the lack of regular raises and promised bonuses, I do get paid on time, properly, and I have an awful lot of fun at work.