Courses can be offered during the workday or at night and on weekends. They can be offered all at once or in small pieces. Thus, courses on the same material might be offered for two full workdays or they might be split into five three-hour classes spread over five weeks.
The choice is one of preference. The more concentrated approach occurs during work and is clearly telling a worker that time out for training is legitimate and the class is important. Classes in the evening say that the material is important but that the worker cannot be spared during the business day. Indeed, the same class may meet during five Friday mornings, if time away from work is acceptable. You just have to decide what is possible and then see what sort of timing works best to meet competing objectives.