In fact, last time I looked Digikey even sold already made ribbon cables. You specify the length, number of wires, and terminations.
IDCs are great for production, but you need a proper punching tool to push the wires down in, just using a screwdriver or something isn't the best way to get results.
IDCs are for manufacturing convenience, but you can also buy the plastic headers empty and loose pins to be crimped onto individual wires, then snapped into the plastic housing. When I was in field service I carried bags of pins and a selection of plastic housings so i could make cables on the spot. These inline connectors like teh KK series, if I carry long cones, I could cut them down to the number o fpins I needed for a particular spot. In other words I might have a 20-pin connector, but lop off all but the last six positions to have a 6-pin connector.