I think that's a great example of the "Peter Principle!"
Honestly, we all know that Trek is chock-full of inconsistencies. It's not actually REAL, after all, and hell, half the world doesn't even care to keep their opinions about "reality" consistent with reality. So it's largely pointless to expect there to never be anything inconsistent with "Treknology."
Still, given all the stuff that's built up over the years, the original concepts (whether we're talking Jefferies, Chang, Minor, Probert, Sternbach, Okuda, etc) are often very well-thought-out... and the inconsistencies crop up later due to other folks not paying attention to the original, well-thought-out concepts. In those cases, I tend to disregard the "bad writing" or "bad directing" or "bad effects" or "bad production" elements and try to stick with the original idea as closely as possible. I don't totally toss the "bad stories" so much as mentally "retcon" them.
For instance, I'm sure that in "real" Star Trek reality (ahem), "Spock's Brain" really happened. But I'm sure that the "real" events were dramatically different than what we saw on-screen. Sort of like what we saw was a really poorly-done "documentary" performed in some 24th-century kid's basement on his eyeball-top-computer.
Actually, "Spock's Brain" could be turned into a decent... even very effective... story. You'd have to totally rewrite it, lose the "Robo-Spock" bit... but the idea of stealing a brain to become the central element of a computer system isn't inherently a bad one, nor is the idea of a society where knowledge has been kept away from the population and only granted... "doled out" so to speak"... when some central power decides it's appropriate.
That would be an interesting project... especially for those here who are more prose-oriented than I am. I'm a big-picture guy and a tech guy... I can come up with great ideas and stories, and I can come up with all variety of technological concepts, but I can't write dialog if my life depends on it!
My point... I engage in "selective mental rewriting" of elements which simply don't work, either in terms of believability or execution. I certainly don't believe that the 1701-D fires phasers from its torpedo tubes, nor that the defiant randomly changes size, nor that every single woman on the "real" TOS Enterprise got the job on some 23rd-century equivalent of Gene Roddenberry's casting couch!
And "Warp 6"... "Full Impulse" is just one of those.
(Either that or Geordi had been drinking... which does raise some interesting "rewriting" options, too!)