Not all spaces need the same cable length. A long ethernet cable helps when your router is placed in a corner or another room. Measuring the distance before buying saves you from short cables. Choosing a length slightly longer than needed gives flexibility. It also makes it easier to reroute the cable around furniture. Proper length means fewer issues with moving or rearranging devices. https://enableit.com/how-long-can-an-ethernet-cable-be/