There are some interconnects and speaker cables with some sort of built in network (e.g., NBS) that means that the cable is "tuned" for a specific length and should not be shortened. Also, some cables are fairly hard to strip and properly re-terminate because they have many tiny conductors that are individually insulated (e.g., Nordost); unless you have a solder pot, these types should be re-terminated by the manufacturer.
If you know what you are doing, you probably can do it yourself. If you screw up, a professional can still probably undo the damage and get it right.
If you know what you are doing, you probably can do it yourself. If you screw up, a professional can still probably undo the damage and get it right.