Since I am just finding this Trek tech thread over here, I'll just point out that I think Maurice discovered the fix to much of the size confusion years ago.
Many folks try to squeeze too many damn decks into the ship, and naturally end up with inadequate headroom when trying to work out the ship's innards versus the canonical length shown in "The Enterprise Incident" diagram of (roughly) 289 meters. Along with some other dubious claims often based on ignoring basic production realities and imperfections, some folks argue for rescaling the ship well beyond that canonical size.
(The rescalers have also tended to latch on to the explicitly intentional "cheat" rescaling of the Discoprise from her originally shown 289 meters to a larger 442 to match the other big ships of Discovery, though even that 442 doesn't leave adequate room for the vast turbolift track caverns we're repeatedly shown.)
Besides the _current vigorous discussion of sizes for the TOS and TMP Enterprise going on in a thread about how one goes from the Cage Enterprise -> Discoprise -> TOS Enterprise_, I started a _thread about the "CONDITION: RED" diagram from Star Trek II wherein the decks are shown_ . . . all 20 of them, no more. If you backport this information to the TOS version of the ship, you find that it works remarkably well there, too, with nine decks in both saucers.
This largely solves the deck height problem that so bothers so many. Instead of hideous deck heights like the Botaitis 2.4 meter (7'10”) Balok-friendly decks, every one of the nine saucer decks of TMP reaches an average of 3.167 meters (10'4" and change), and this applies to TOS also (but for deck two's portion beneath the sunken bridge).
Naturally, there are odds and ends (e.g. Michelson's Folly, the intentional building of the TMP Rec Deck with no consideration of scale and ship fit, or quick-we-need-a-corridor-ceiling-for-this-low-angle-shot slap-up jobs, or decisions to make the shuttle comfortable to film in, et cetera), and minor other hiccups here and there, but considering the massive failures of scale in the CGI era when there's far less excuse than in the slide-rule-and-paper era, I think it should be quite easy to live with the canonical scalings for TOS and TMP.
That said, 442 meters is canon for the Discoprise -- after they chose to changed from showing 289, and only if you ignore the caverns -- so do with that seeming contradiction what you will.
Many folks try to squeeze too many damn decks into the ship, and naturally end up with inadequate headroom when trying to work out the ship's innards versus the canonical length shown in "The Enterprise Incident" diagram of (roughly) 289 meters. Along with some other dubious claims often based on ignoring basic production realities and imperfections, some folks argue for rescaling the ship well beyond that canonical size.
(The rescalers have also tended to latch on to the explicitly intentional "cheat" rescaling of the Discoprise from her originally shown 289 meters to a larger 442 to match the other big ships of Discovery, though even that 442 doesn't leave adequate room for the vast turbolift track caverns we're repeatedly shown.)

Besides the _current vigorous discussion of sizes for the TOS and TMP Enterprise going on in a thread about how one goes from the Cage Enterprise -> Discoprise -> TOS Enterprise_, I started a _thread about the "CONDITION: RED" diagram from Star Trek II wherein the decks are shown_ . . . all 20 of them, no more. If you backport this information to the TOS version of the ship, you find that it works remarkably well there, too, with nine decks in both saucers.



This largely solves the deck height problem that so bothers so many. Instead of hideous deck heights like the Botaitis 2.4 meter (7'10”) Balok-friendly decks, every one of the nine saucer decks of TMP reaches an average of 3.167 meters (10'4" and change), and this applies to TOS also (but for deck two's portion beneath the sunken bridge).
Naturally, there are odds and ends (e.g. Michelson's Folly, the intentional building of the TMP Rec Deck with no consideration of scale and ship fit, or quick-we-need-a-corridor-ceiling-for-this-low-angle-shot slap-up jobs, or decisions to make the shuttle comfortable to film in, et cetera), and minor other hiccups here and there, but considering the massive failures of scale in the CGI era when there's far less excuse than in the slide-rule-and-paper era, I think it should be quite easy to live with the canonical scalings for TOS and TMP.
That said, 442 meters is canon for the Discoprise -- after they chose to changed from showing 289, and only if you ignore the caverns -- so do with that seeming contradiction what you will.