I am installing (6) brand new smoke alarms in my home, including running all new 14/3 wire to each alarm. I have purchased "old work" electrical boxes for all of the alarms. However, the existing smoke alarms are installed by just screwing the bracket on to the stud and cutting in a small hole next to the stud to route the wire down.
I know the electrical box would probably be the best method, but it seems the advantages of just mounting to the stud and cutting a small hole would be (a) smaller wall cutout and (b) quicker/easier install time.
So the question is: Should I install smoke alarms in an electrical box or mount them directly to the stud?