A layer of mixed-resistance structured packing includes: a first structured packing having a first packing resistance; and a second structured packing generally horizontally adjacent the first structured packing, the second structured packing having a second packing resistance different than the first packing resistance. The layer of mixed-resistance structured packing is used in exchange columns for exchanging heat and/or mass between a first phase and a second phase in processes such as cryogenic air separation. Use of the layer of mixed-resistance structured packing reduces HETP (height equivalent to a theoretical plate) in the exchange columns and processes. A method also is provided for assembling the layer of mixed-resistance structured packing in an exchange column.