A cut-to-length steel coil processing line has an un-coiling reel, a temper mill, a stretcher leveler, a shearer, and a stacking apparatus arranged to sequentially process a continuous length of sheet metal. The line may be configured such that the continuous length of the sheet metal is directed from the uncoiling reel through the temper mill to the stacking apparatus without processing through the stretcher leveler when a determined thickness of the continuous length of sheet metal is at or below a selected measurement criteria. In the alternative, the line may be configured such that the continuous length of the sheet metal is directed from the uncoiling reel through the stretcher leveler to the stacking apparatus without processing through the temper mill when the determined thickness of the continuous length of sheet metal is greater than the selected measurement criteria.