This is the default in the Netherlands for many office jobs as well. Usually in the form of 'Subclause 2: The nature of the job may demand work beyond the state

This is the default in the Netherlands for many office jobs as well. Usually in the form of 'Subclause 2: The nature of the job may demand work beyond the stated hours in subclause 1. If this occurs, no additional payment shall be made'. Never had a job where that wasn't a clause in the contract.