Speaker cable length for L/R channels critical?

Explain how come man can tell difference between a tweeter rolling off at 22Khz and a tweeter rolling off at 33Khz, when we should not be able to.

Simple: The tweeters also differ in the audible range. As for why companies are making such tweeters, why do amp manufacturers make amps with 0.01% THD, when nothing under 0.1% (and probably 0.5%) is audible? Possible answers: Because they can, because there are people who will buy them for whatever reason, because there's nothing wrong with building in a little extra margin, and because there's the challenge of taking something to the limit.

As for cable lengths, we agree more than you might imagine: I don't think different cable lengths matter, but I keep mine the same length anyway. Habit, perfectionism, superstition, whatever...

My experience suggests that the overall sense of hearing extends well beyond the frequency at which a pure sine wave test tone can be heard. In other words, introduction of roll off by a filter, say at 16KHz is easily sensed by someone who can't hear higher than 12KHz in a hearing test. I observed this in my own case and of course I wanted an explanation. I think that the reason is that the sense of hearing perceves not just the change of air pressure, but also the rate of change, and an irregular waveform, like music, has steep wavefronts. A tweeter with extended frequency response can generate these steep wavefronts, and sounds better than a tweeter with frequency response that only corresponds to the "official" audio frequency range.

Also note that the difference between 22 KHz and 33 KHz is not as much as you might think...only one half an octive.

Also:
2 tweeters that roll off at the example freq or 22khz and 33khz will also have a phase shift difference even well below their roll off freq, in the audioable range. Much of music is composed of impluses which are composed of the fundamental freq and some harmonics of that freq. If the phase relation of these harmonics are affected by the tweeter roll of freq, then you change its sound.

does this explain why, when I turn on my sub, the entire frequency range that the main speakers produce, top to bottom, sounds richer to me? I've wondered about this recently.
Thanks,
Art

OK, so here is a question.

What is better? To have a 4 foot and 10 foot run? or to have two 10 foot runs where the excess cable will end up spooled on the floor?