Not best practice, no but in my experience it is difficult to get a plasterer to avoid filling a box completely! There is quite a bit of overlap on the socket front so you can get away with a few sins. With care, you can chop a box in and not need to repair the existing plaster.

Not saying they are perfect but seem to be designed around plaster and block walls compared to the ones in the above pictures which seem to be more suited to plasterboard walls.

I took my time, I hurried up, The choice was mine, I didn't think enough