Length of SPDIF cable

I've just ordered a Xangsane pure silver SPDIF coax cable and it's already on the way. I've ordered a 1m cable because I've read that "you should not have a too short SPDIf cable". My previous ones were all 0,5m.

But now I read that the ideal length would be 1,5m which kinda makes me wonder if 1m is not just the "wrong" length.

Well I will listen to it, I suppose if it sounds good it's good, but still, why don't they only make 1,5m coax cables if that is the recommended length?!?