In my racks:
- My RCAs are custom length.
- My speaker cables are cut to size.
- My HDMIs come in .3, .5, .7, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, etc meters
- My CatX cables come in feet lengths of .5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9,10, 12, 14, - 15, 1,7, 20, 25. Anything longer than that and I'll either cut a long cable so that I only have to re-terminate one end or they end up on patch panel.
- Power cables (IEC) 1, 1.5, 2, 3, 4 & 10 feet. The 6 footer is the standard one. Seems like other power cables are smaller and can be coiled and zip tied.