Real proportions
A bathroom that is 1.7 metres wide comes back 1.7 metres wide. Tile scale reads correctly against it instead of being invented.
Bathrooms
Tile it on screen first.
Small rooms punish mistakes. See tile, sanitaryware and lighting in your actual bathroom, at its actual size, before the first box is ordered.
Soil pipe stays put
The positions that cost money to move stay fixed unless you deliberately ask for a replan.
Tile before you order
Large format against small, dark grout against light, on your own walls rather than a showroom board.