I have looked at this site for very many years. The Soundwest site has enough errors to mislead someone relying upon it for 'basic information' and a bit of the math.
In its Section one, the author does not understand a tweeter is still not time coherent when its wires are flipped over to invert its polarity (paragraph 3). He goes on to mis-represent the amount and degree of cancellations between mid and tweeter when the tweeter is not in the right position (below Fig. 5). What he presents instead is a graph showing TWO IDENTICAL, PERFECT, FULL-RANGE DRIVERS interfering, not a graph of one mid crossing over to one tweeter.
In its Section two, the information in the paragraph below Fig. 10, about phase shift and its audibility on square waves, is just plain wrong (even stating we can't hear it, then giving real examples of how we can hear it).
In Section four, on the audibility of phase distortion, not only is he wrong about its audibility, but he goes on to present an argument based on sound coming from live instruments.
He does not get it that we want to PRESERVE whatever phase relationships exist in the music, no matter where we sat, no matter where the recording microphones were placed. Can you spot the big flaw in his argument based on hearing live music? I have seen this exact bad-logic presented on many other forums as the main reason not to bother with making speakers time coherent.
In his Conclusions, he claims the room acoustics and bad recordings will hide much of what should be gained from making the speakers time coherent. To me, that makes it obvious he's never lived with time-coherent speakers for any length of time.
He mentions how a little pair of speakers in his workshop will reproduce a square wave at one frequency if he holds the mic in just the right place. I can see he does not recognize those speakers likely still have a phase shift of 360 degrees at some frequency, and how that will make a CONTINUOUS square-wave signal still appear square.
He does not remember that 360 degrees of shift at some frequency means the previous square-cycle is then projecting/delaying some of its frequency-components INTO THE NEXT CYCLE, and so on. He should have been examining only the first half of the very first square-wave cycle-- its first up-and-down only, to figure out what a speaker is doing.
His are the answers I find quite common on the web, but not in most of the professionally-reviewed papers published by the AES. Their important papers on speaker design can be purchased by anyone as their three Audio Anthologies books. There are still errors in too many of those, but one must know calculus and physics quite well to find them.
I think the general public should not take a writer's claims about audio design for granted, unless the writer also presents the scientific concepts and logic behind those concepts, and WHY those have to be correct. Which is what I've endeavored to do.