Seat Depth Is the Specification Nobody Checks
People choose sofas by looking at them and, if they are careful, by sitting on them for thirty seconds in a showroom. What actually determines whether a sofa is comfortable three years later is a set of dimensions almost nobody asks about: seat depth, seat height, back angle and arm height. Depth is the most consequential of the four. Too shallow and a tall person is cut behind the knee and slides forward. Too deep and a shorter person cannot reach the backrest without their feet leaving the floor, so they end up perching or piling cushions behind them.
This design is built deliberately deep, for people who want to sit sideways with their legs up rather than upright with their feet down. Everything else follows from it. The arms are low, because high arms are an obstacle when you lie across a seat. The back is buttoned rather than loose-cushioned, because a loose back cushion on a deep seat slides forward every time someone moves. The seat cushion runs unbroken across the width so there is no join under your hip when you turn sideways. None of that is decorative; it is what the depth requires. And because we build to order, the depth itself is a number you choose rather than one you inherit.