Back in the old days of analog video, component video was three separate cables. When we made custom cables, we had to ensure the cables were the same length to ensure the timing was within tolerance. The day we got to switch to digital SDI which also included audio as like a gift from the gods
This was probably also due to impedance matching between all the lines involved.
Digital signals (when using N/P balanced lines) also have this problem, to a lesser extent. Some CAD EE design software have ways to design squiggly traces to balanced impedances in traces that have to go around corners on the PCB and end up with different lengths.
This is still a problem for modern multi-lane digital connections, like PCI Express. The solution? Make each individual lane self-timing, and compensate for it digitally in the receiver buffer.
