It depends on the amount of hrs accrued, your weekly avg & how many you wish to use.
Ex: Say you've been with spot for five yrs, you avg 32 hrs/week & you can accrue up to 2 weeks of vay-cay a yr.
You've got 41 hrs banked & you want to take a week off.
You can only use up to your avg, 32 hrs in this case but that leaves you 9 hrs still banked.
Inversely, if you avg 38 hrs/week but you only have 16 hrs banked, that's the max you can get paid for until you earn more vay-cay.
As long as you have vac hrs banked, there's really not a limit as to how often you can request them.
HOWEVER, you can't request extra hrs OVER your avg.
Ex2: Your avg is 36 hrs/week, you only worked 30 so you want to use some of your vac-cay to supplement your pay.
Based on your avg, you can only add 6 hrs.
Capiche?