The feature wall usually ends up behind the toilet — the one wall nobody looks at while using the room, that the mirror never reflects, that spends its life behind a person's back. That misplacement explains most bathrooms that disappoint despite good materials. The effort went where the eye does not.
Design in a small room is decided at the door. Whatever faces the entry is seen dozens of times a day from the hall, door open. That sightline earns the interesting tile and the depth — usually the shower back wall, read through glass and lit from inside, or the vanity wall, framed by the mirror. Flanking walls are read peripherally and can afford to be quiet.
Setting-out is never specified by homeowners and always noticed afterwards. Tiling from one corner leaves a sliver at the other, and a cut narrower than about a third of a tile reads as a mistake and chips at the edge. The grid is set from whatever the eye uses as a reference — a niche, a window reveal, the vanity centreline — not from wherever tiling began, and floor cuts get pushed under the vanity and to the threshold. Horizontals matter more than verticals: the top of the tile field, the niche shelf and the shower valve either agree in height or visibly do not, and agreement costs nothing at setting-out and cannot be added afterwards.
Material count is where restraint pays. Counted honestly — floor tile, wall tile, shower tile, vanity front, counter, mirror frame, glass hardware, paint — a busy bathroom carries eight materials in four square metres. Three plus one metal is about the limit a small room reads as deliberate. Grout is one of the three: a contrasting grout turns a tiled wall into a grid pattern and roughly doubles its visual weight, which is a decision, not a chart picked from at the end.