Management of Overtime/ Time off in Lieu. An Employee shall not work overtime without first obtaining the express approval of his/her manager. Where an Employee works a significant number of authorised hours in excess of the ordinary hours of work, on other than an irregular and infrequent basis, the Employer may investigate the cause of the requirement for such excess and take appropriate action, including an assessment of the workload involved where appropriate, to ensure that the Employee works only ordinary hours of work on a regular and frequent basis.