The Long Service is calculated based on the number of units worked times the LS Accrual rate.
If an employee is FTE = 1 and you pay them by the day and they work 10 days per fortnight and they accrue 1.4 weeks per year worked then their accrual rate will be 1.4 / 52 = .0269
Then for each day worked they will be awarded ls accrual of .0269 days and for a 10 day fortnight they will get .269 days
If the employee is Fte .5 but works each day in the fortnight then you would pay them for either 10 half days ie 5 days per fortnight or if by hour pay for 35 hours per fortnight. In this case they accrue per fortnight half the accrual for the FTE 1 person. The system bases the accrual on the hours worked and not the FTE of the employee however hours worked should reflect the FTE of the employee.