Leave approval was added to TimeTrak in version 23.1 as per below:
https://timetrak.co.nz/blog/category/leave-approval-in-timetrak/#approving-leave-in-timetrak-professional

This has been enhanced from version 23.1.1 with the added ability to filter by the Leave type as per below:

This functionality has been added to assist leave approvers processing a large number of leave requests.

Once filtered by the leave type, the leave ca be approved for all staff.
A working example of where this is helpful is over Christmas, leave approvers can filter Statutory holidays and approve these for all staff at once;

Once a leave type has been approved for all staff, either change the filter or hit refresh to see remaining Leave Requests and approve where applicable.