The combined timetable represents the teaching week as a grid. Each activity that is associated with an item selected in the Views pane is displayed in the grid, within the cells that represent the periods the activity is scheduled for. You can see the selected items' activities for the whole week, without any need to scroll.
You can use the combined timetable to find a time when all the items selected in the Views pane are available. To display possible start times for new activities, and times that the selected activities can be rescheduled to, see Indicate when an activity can be scheduled.