The answer to this question has recently been given by the National Court, and through a ruling, it makes it clear that the travel of a worker from his home to that of the client, and also vice versa, is considered effective working time, specifically in cases in which the activity of a company consists, for example, of the preventive or corrective maintenance of the machinery of its clients, and that this is located at the latter's home, such activity could not be carried out if there is no travel to the client's home, therefore all travel becomes co-substantial to the company's activity.
More generically, the Law considers effective working time those trips during which the staff is in the exercise of their functions, and therefore is at the disposal of the employer, and also if they carry out their functions during the time of travel to or from the client's home.
Time control systems, such as Timenet, allow the worker to very easily register the start of their workday right when they leave their home, and also the end when they return home, after having made all the journeys required by their activity.