Oh no no no. That wasn't the intent. First, to clear up the non sequitur here, I can mention one and only one cellular response to training if I want to and it doesn't follow that I see that as the only such response from said training or that it was a "sciolistic attempt" at anything. The fact somebody might read it that way doesn't make it that way.
Now, if fizzy-o-malogical responses were the only reasons for doing a certain workout (and people who do approach it from that angle are missing some of the point), there is unquestionably a whole long list of itty bitty cellular responses that occur at 3k pace which aren't as pronounced at 5k pace (even if you run longer at 5k pace), and - although practically insignificant as stand-alones - the sum of those tiny benefits does carry some weight. If it sounded sciolistic, maybe it's because I only included one of those small benefits. What I am supposed to do? List them all? I didn't have time and I didn't feel like typing anything else at the time anyway. I'm pretty sure nobody knows them all anyway, but if I had listed a dozen more of those little cellular responses, would that make the info less sciolistic? ... or more sciolistic because there was more fizzy-o-crap? Maybe if I added this: "None of these changes is overly significant in itself, but taken together, they confer a slightly different overall benefit than you'd get from running at a slower pace." Something tells me that would still be more than pedantic enough for "J.O.," who came off as snooping around for something to be contentious about. Maybe if I listed none of the cellular responses ... naaah. See my third sentence above. I can mention one if I want to.
In any event, I never did attribute the mitochondrial boost as "the" reason for that workout (IIRC, I mentioned 2 or 3 other benefits to be had). Actually, it's not even "a" reason somebody should choose to do 10 x 400 instead of 20 x 400. It's just one small effect bestowed by having done the work. The other things I mentioned, specifically the variety and the familiarity with another pace, are better as reasons for doing different workouts from time to time.
Obviously there's some kind of misunderstanding on one end or the other regarding those numbers. But as long as we're all piling on ... "20 x 400 at 600 to 800 pace? BOLLOCKS!" from me as well.