

No, 2 shifts means there just a day and night shift, each 12 hours. Half the people from each shift are rotated off each day and night for normal operation. You end up working about 42 hours a week, but its all clustered so you get a clear divide between half of the week when you just work and sleep, and the other half where you are off.
Its popular with the military because you can easily surge staffing or fill in missing people without messing with sleep schedules. Ideally, you can double manpower at a moments notice just by canceling days off, where as with a more traditional 3 shift rotation youll have to pull from other shifts since they only have 2/7th of their manning on break at any moment.
My theory has always been that Vic was actually the “puppy” computer virus from s01e16, growing up and trying to get more interaction with people. That’s how he could transfer himself between holodecks and access station systems. In the mirror universe the virus infected an android body and not a holodeck program.