In Web TimeSheet it is not possible to setup multiple 'Hours Per Day'. If an employee works for different hours in a week eg., 8hrs on Monday or 4hrs on Friday during the week then leave the default hours per day as 8hrs. If a user wants to book a timeoff that happens to fall on a day when the employee works for 4hrs, then the admin or employee can manually book a Partial day timeoff and enter the number of hours that they usually work on that day which is 4hrs.