Below article from The Klipsch Audio Community:
This entire thing goes back to the Eleanor Powell "double tap" incident at MGM studios in the early 1930s. When monitoring playback of Powell tapdancing an echo was noticed on the taps. John Hilliard, subsequently the greatest of all horn designers, was a young sound engineer at MGM and traced the problem to the 8 foot difference in the path lengths of the horns in the 2-way Western Electric monitor speaker.
Hilliard did experiments that showed that the effect was time and frequency dependent and that a delay of less than 3 milliseconds (about 3 feet) was inaudible using crossovers between 350 to 800hz.
A result of this incident and WE's refusal to market their improved Fletcher loudspeaker was the decision of MGM sound honcho Douglas Shearer for MGM to design their own improved system which would among other things minimize time delay. Hilliard was put in charge of the project which then developed the famous Shearer Horn. An entire galaxy of talent worked on this system including Hilliard, James Lansing, Bob Stephens and even RCA's Harry Olson.
Note that though the folded bass horn of the Shearer cut time delay compared to the WE snail horns it didn't eliminate it totally but Hilliard's later Altec Voice of the Theatre did. So it seems that even though Hilliard thought some delay was inaudible the existence of any at all still nagged at him.
Which brings us back to the present day. Is the time offset of the big Ks a problem? Theoretically the distance falls under the distance Hilliard thinks was undetectable. Might it still be a problem? Perhaps. But keep in mind that all loudspeaker designs make compromises, given a choice, as PWK was with his design, between lower distortion and time delay which would you choose? I'd take the lower distortion of the horn system.
Photo of Shearer Horn from Lansing Heritage site
https://www.tnt-audio.com/casse/altec_a7_clones2_e.html