I always just bought the shortest length shunyata PC that would reach and leave some flexibility to save $$$ and have always been happy.
Anyway I bought this Wireworld Cable mini plug for a Devialet Phantom and was surprised to read what they said about length. "Since they function as filters, longer lengths improve performance." Great PC by the way. The Phanthom's sound got fuller, richer and better overall. Perhaps because as Class D it needed thicker guage power cord for passages with heavier current draw?
https://wireworldcable.com/collections/power-conditioning-cords/products/electra-mini-shielded-power-conditioning-cord