Marble is chosen twice. Once for its colour, which everyone thinks about, and once for the direction of its veining, which almost nobody does - and the second choice matters more on a long top than the first.
Veining in a slab runs in a direction, and when a top is cut from it that direction is decided by how the piece is laid out on the block. Cut so the veins run across the width of the table and they read as a series of bars, dividing a long top into segments; the eye stops at each one and the table looks shorter and busier than it is. Cut so the veins run along the length and they carry the eye from one end to the other, and the top reads as a single unbroken surface.
So our master Indian artisans lay the template on the slab with the veining running lengthwise before anything is cut, and where a slab has a strong figure, the template is positioned so the most striking passage falls at the centre front - the part of the top nearest the person standing at it.
The offcut is not the waste. The layout is.