Hi,
The other day I was working in a house about 5 years old and I saw
something I thought was neat, wondering how prevalent it is. To fill
the gap between the front of the electrical box and the surface of the
sheet rock, the electrician threaded the outlet/switch mounting screw
through a short scrap of romex sheath that could squish down and keep
the switch/outlet forced out away from the box, flush with the wall.
Is that common? new? good idea? bad idea?

Whenever I've had that problem in the past I would just put a bunch of
small washers on the screw. I didn't know if I should switch to doing
this instead.