Why accruedSalary sets to 0 on payday?

[devmerit]

payroll-app/contracts/Payroll.sol

Line 317 in 8b097ec

employee.accruedSalary = 0;

Each time an employee is getting his salary via payday function the accruedSalary is set to 0. But what if his _requestedAmount is less than accruedSalary? In that case all his accruedSalary will be terminated without payout.