The employer I worked for operated under one of the 2 systems allowed by New Zealand law. Leave is accrued as a percentage of hours worked. Overtime and penal rates could have one of two effects. Either the hourly rate payed out when on leave was increased, or the amount of leave you got increased as you did more shifts, call etc. They did the latter. The odd bit was that you earned leave while on leave (which I supposed has to happen). So after I was paid out when I left, I wrote to them and asked if the 3 months leave owed entitled me to an extra percentage as I'd have earned leave while on leave had I taken it. They paid me. So I wrote again, and they paid me again. Obviously this had rapidly decreasing returns, but it struck me as rather funny.