Why "where to start" matters
Laying full tiles flush from one wall is the easy way, but it leaves the whole leftover as a single cut against the far wall. If that comes out as a thin sliver it is fiddly to cut and the eye goes straight to it. The trade rule is to keep every cut as large as you can and never below about half a tile, so when a flush start would leave a sliver, Setout centres the field instead and splits the leftover across both ends. These are planning figures: always check them against the coverage printed on the tile box, and dry-lay a row before fixing anything.