I don't particularly recommend that specific cable, I found it a bit fragile, but I can't say I know what to suggest as my other multi cable is scavenged Mogami 8ch that is probably at least a decade old. You should be fine with mono on a stereo cable. Just make sure to connect the second wire to signal, ground, or seal it so it's not at risk of any funny business.
Super useful to know! Wll in that case maybe I'll go down the separate cable route and wrap them/bind them to keep them tidy. Tbf at least separate cables are much easier to replace if one breaks etc.
I'll use decent quality cable for all of them except probably the footswitch one where I don't need to work as much about interference etc.