In Austria we use only radial circuits, usually 1.5 sq. mm fused 10/13 or sometimes 16A (different values for fuses/breakers), lights and sockets usually mixed. Walls are typically brick, directly plastered (We don't bother with horsehair, bonding agent,... and whatever I've heard about US plastering, our plaster is lime with sand and usually (not necessarily) cement, older plaster is just plain mud mixed with water, sandbox style) sometimes 2" or 3" gypsum mixed with lumps of steel dross (hope I got this right out of the dictionary, it's some remnant of the steel production), supplied in panels 30x60 cm for interior walls. Plaster and lathe was commonly used for ceilings, for finished attic walls and in rural wood structures, always with straw mats nailed onto the lathes for better keying. Wiring is run within the walls, either NM direct buried or THHN in PVC flex conduit. Junction boxes theoretically have to be located above each switch and receptacle (both to avoid too many bends with conduit, and to be able to guess where the wiring runs without having a map.) I hope I can find room wiring schematics and post them. Ceilings contain only the wires to the light fixtures. For adding outlets or anything else it's usually inavoidable to get a sledge hammer and a good chisel, or better a rotary drill hammer with a flat chisel bit. (Myself I use a Bosch hammer for roughly $159.90, 159.90 Euro, Hilti hammers are also very common).
Personally I prefer ripping up walls over fishing in cavity walls, you can see what you're doing. Wires within wall/ceiling vavities MUST be in conduit.
In the 1970ies and 80ies the use of drywall with standardized aluminium profile studs (Knauf has almost a monopoly on them, Rigips, a brand name, has become synonymous for plasterboard). These studs have KOs for conduit I think every 50 cm.
However, exterior walls are still typically brickwork.
