I am sure you have something planned for time estimation and tracking. A simple implementation could be the following:
Record Time: User can enter any time spent on that entity in terms of hh:mm or from-time to to-time. These records create a Time Log for the entity and also gets added to the Timesheet for the respective users.
Time Spent: Always shows the total duration of time spent on the entity (like task). This is calculated from the logged time.
Time Log: Shows an expandable list of all time logs recorded for this entity by all users. Shows date, from-time to to-time (optional) and duration.
Estimated Time Remaining: At the start of a task (entity), user can enter the estimated time required to work on this task/entity. Afterwards, it is updated by user to always reflect the time actually remaining to finish the task at any point. This is NOT calculated. User can edit this field and enter the time that is estimated to be remaining for that entity at any time, reflecting the real situation.
Timesheet: Standard timesheet for the user, collating all time spent in all entities, shown for each day of a time period, with totals for day and totals for period. A supervisor can view all subordinate users timesheets.