This is again based on the defined leave policy of the company. A company grants eligible number of leave days to employees periodically. For example, 18 days Earned Leave for every completed year of service or 1.5 days EL for every completed month. Similarly, other leave types also can be granted. Tracking all transactions is important because at any point of time HR needs to ensure that leave balances are accurate.
Line Managers need access to leave balances of their employees to aid in decision making on approval of leaves. They need to know the leave details of an employee and peers who are on leave in that period. HR needs to give them this information. In case of issues regarding non-review of leaves, etc. HR needs to work with the Line Manager to ensure a smooth working of the process.
There will be cases when an employee requests for a compensatory off (additional leave days) for working on holidays/weekends. HR needs to ensure that this is tracked and appropriate balances are updated.