When I built my place I used mounting blocks on all power points and switches. When the plastering/mdf-ing of walls was done, cables were pulled through holes just big enough to accomodate them and then caulked around them. Mounting blocks were used to make enough space between the wall and the surface of PP and switches to fit the protruding cables in. The mounting blocks are screwed into the wall cladding (plasterboard and/or anything else you're using) and the top plate of PPs/switches screw straight into mounting blocks. If you're using plasterboard only you need some raw plugs (
http://compare.ebay.com.au/like/1708936 ... eItemTypes ) to ensure safe fastening of the mounting blocks. I had MDF on my walls, so I just went straight into that.
This is a much more efficient way of doing it than using the conventional 80X50mm cutout (or whatever the size is).
This leaves you with a huge hole to caulk.
Many studios that want to minimise holes in their walls, bring the power cable into a room through a single whole and then distribute the power within the room via surface-mount conduits. I considered doing this, but it just doesn';t look good with pipes running all over your walls.