According to the Workers' Statute, a person's working day may not exceed "40 hours of effective work per week on average in annual calculation", although very often these hours are multiplied because they end up being "overtime hours" in periods of high workload; in this case, it must be taken into account that these also count for the worker, but independently of the working hours, so that the limit that can be made of this type of hours per year is 80.
Overtime hours will only be done if the person wants to do them and is over 18 years old, they must be duly registered, and also remunerated, either in monetary form (with a value higher than the conventional hour) or compensated with breaks. In the event that these hours are compensated for breaks, they will not be calculated as such in the 4 months following their completion.
What can be done is to distribute these hours by contract or labor agreement according to the convenience of each company, but at least 12 hours must have passed between the end of one day and the beginning of the next.