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: cmd + alt + mouse click on the desired shifts
Select the whole day: cmd + alt + mouse click on the desired day
Select all shifts: cmd + alt + A
Copy selected shifts: cmd + alt + B
Paste copied shifts: cmd + alt + V
IMPORTANT: Your selection will also stay active if you change the week or month.