Actually, no. The "common" (too short) size comes from these Jefferies' sketches: In which you clearly can see that the Enterprise was still in the stage where the saucer was only one(!) deck tall. When they built the actual model, they changed the size, by including an additional row of windows on the saucer's edge, making it two decks tall. (Of course the window-size was then off-scale, they are rather large for two decks, but the TMP-refit adjusted that as well with having smaller windows along the saucer and body) And again, not really. With two decks in the saucer, the size simply doesn't fit. Here is Doug Drexler's famous cut-away, in which he tried to fit two decks into the saucer and make the shuttlebay as close as possible: But the thing is - he cheated. The humans in this picture would be midgets, and the decks only ~2m tall, even without the overhead-space that he already ommited for that picture. And the shuttle is somehow even smaller than a single deck. The truth simply is - the "common" size doesn't fit. It was envisioned for a ship half the size, that was then upscaled before production to double the size. Otherwise, 100% agreed with everything else you wrote here.