Since the employee is a senior and an efficient employee, the HR has to make the him feel how important he is for the organisation and how he should abide by the company policies and be an example for others and it should be explained that it might create conflicts among other employees if he is given holidays alone . He has always been in the good books and such demands are not expected out of him. However if he still insists and there is any scope for adjustments then the work days can be made 5days with increase in the no of hours with the consensus of the other employees too.