I did not know that.
The electricians I hired were not top rate and there were lots of fumbles.
They told me the usual method is to set the boxes flush with the studs, and then use mud rings to make up the difference between the stud and finished wall. I followed their instructions and ok the work so now all the boxes are flushed with the studs, not easy to move since that's all rigid EMT conduit work.
Some of the boxes have quite a bit of wires, the electricians told me to put mud ring on and that keeps the wire coiled in them until I am ready to install the switches and outlets. Seems to make sense to me at the time, I thought about sheet rockers using rotozip to route out the box, but subconsciously I ruled that out because I thought with the wires in them the rotozip would end up piercing the wirings at best, and since I used all double gang boxes even though many of them will actually be single gang outlets or switches, there is no way they would be able to cut them correctly without the mud ring on. I used double gang boxes because I ran into problem using the single box before when I need to put in those big thick GFCI boxes it does not leave a lot of room for wires especially if the box also serve as a junction box so I prefer to do that to have some extra room if needed.
I didn't really think through this whole process. I am still a bit confused about using a rotozip to cut around the inside of a box wouldn't that have a pretty high likelihood of tearing into the wires in the box and what about where I would have a single gang switch/ outlet but I used a double gang box.