I have a question regarding the changes made to the interior sets between Star Trek IV and Star Trek V. Namely, the Engineering set underwent the greatest change, being the biggest set in the films (aside from the massive shuttlebay in TMP). While I understand that the bridge set was destroyed between the two films, I was never told why the rest of the interior was changed as well. Below I examine the changes.
STAR TREK TMP - IV
We have the same Engine room for the first three Star Trek films, so understandably the same Engine room was probably intended for the Enterprise-A in Star Trek IV. At least, I can't see why it would need to be changed.
STAR TREK V
Here we see a much smaller engine room. I like it a lot, but where's the engine? And where are all the engineering crews? Surely it takes more than one man to operate a starship engine room.
STAR TREK VI
What the...? What is this!? Why does a 23rd century Enterprise have the EXACT same engine room as a 24th century galaxy-class starship? I mean, come on! That's just lazy set design!
Conclusion: Does anyone know the real world reason for the set changes made to engineering for the Enterprise-A? If you do, please let me know!