To make using the roster even more efficient you can use hotkeys in the calendar view.
The following hotkeys are at your disposal: (Keyboard combination for mac. On Windows PCs use "Ctrl" instead of "command")
- select multiple shifts: + + mouseclick on the desired shifts
- select the whole day: + + mouseclick on the desired day
- select all shifts: + +
Your selection will also stay active if you change the week or month.