How important is a (historical) time record in SAP HR for manager and employee?

Sorry, I'm not SAP HCM Consultant 

sorry i didn't work in sap system before

Historical time record in SAP is very important as the Manager can see everything at a glance the chronological events of what happened and when. Similarly, the employee will be able to know from HR Manager, the actions already taken by the employee and future action thereof. The contents SAP HR module available to HR Manager and the content of SAP HR Module available to employee may not be the same.