is there a consensus on too short speaker cables?

I am not sure you will ever find a consensus here. FWIW, the difference in sound between 5 foot and 6 foot is negligible but the distance from amp to speakers can easily be more than 5 feet.

Like Shadorne said, a consensus will be hard to find. BUT: There are a lot of us out here that are using monoblocks, placed as close as possible to the speakers. As long as the cables are a popular brand/series: You've sell them. I just listed a pair of my old Audioquest bedrocks(6 ft long, from my bedroom) for $75.00 on eBay, and have a bid from someone in Poland already.

Like so many voices here I am not taking any side exept what my ears tell me. Your situation might be different then X or Y. It comes down to practicality, shielding/isolation, quality and interference. My cables are top of the line Vampire ( custom made biwire ) 12f long which I will be getting out of my system soon. These will be replaced with 4f biwire Morrow Audio. In my case, shorter runs are preferable since the very close placement of my mono-blocks. It is also recommended my Mike from Morrow but that is not the reason or rule that one should go by. It is prefer by some and cursed by others. Opinions about that matter goes block by block, dealer to dealer. You will have to make that decision yourself - unfortunately .......or not.

My thoughts are that if the cables won't reach the speaker posts, they are indeed too short.