A waisted case looks like one shape and is really three problems.
Because the front pulls in below the top and swells again at the base, every horizontal section through the piece is a different size. The carcass sides are not parallel at any height. And - the part that catches people out - the drawers cannot be identical, because each one sits at a different point on the curve.
So they are built individually. The top drawer is shallower front to back, since the case is drawn in where it sits. The middle drawer is the deepest, at the widest point of the swell. The bottom drawer follows the curve as it turns back inward. Each front is shaped to the case's profile at exactly that height, and each box is made to fit its own opening only.
That is why our craftsmen build the carcass first and complete its shaping before a single drawer is started. Working the other way round - making drawers to a drawing, then fitting them - would mean three boxes that are each slightly wrong in a different direction.
Every drawer is marked to its opening, and once fitted they are not interchangeable. Put the top drawer in the bottom opening and it will go in, sit loose, and never look right.