A millimeter in industrial-design drawings is a theoretical quantity. A millimeter in a sectional sofa is an inch of perceived space once the piece is sitting against a wall, under a ceiling, with a rug in front of it. We draw everything at full scale on the workshop floor before a piece of hardwood is cut, in part because that's the only way to know whether a 132-inch sectional actually wants to be 134.
We work to the millimeter when asked. A seat depth adjusted by an inch. An arm reduced by two. A sectional sized to a bay window rather than rounded to the nearest catalog cell. The frame is still ours — its proportions, its joinery, its tolerances. The dimension is yours.