I've already had my say on this in my own way:
The 22ft. exterior mockup is obviously too small to hold an interior even remotely resembling what we saw onscreen. So at best all you can do is put something rudimentary into it. The exterior was made smaller so it could be more easily transported and more easily handled on set.
The interior set is impossibly large and if you scale up the exterior (to about 32ft.) to hold it you end up with an exterior too large to be properly accommodated within the Enterprise's
The miniature seen in the hangar interior shots is also slightly too small while the flight deck itself is slightly too large.
The best is to compromise and there are clues in the series (most notably "The Galileo Seven") that the problem was recognized and there are hints the interior was meant to be smaller than what we were seeing. The interior set was made fullsize to accommodate the bulky filming cameras of the era.
The compromise I came up with several years ago was about 26-1/2 ft. The interior is scaled down some, but it's still immediately recognizable with only the loss of some headroom and some cabin length (and there was plenty to spare on the fullsize set). The exterior looks exactly the same as seen onscreen.