Which would indicate a REALLY hasty refit since only a matter of weeks passed between The Voyage Home and The Final Frontier![]()
We don't know how much time passes, not really.
1) Scotty huffs and puffs about the time Kirk said "Let's see what she's got" as if he hasn't had time to discuss the issue before - but Uhura's response could just as well indicate Scotty has been saying the same thing for the past two years, over and over again.
2) Kirk gave Scotty three weeks to patch up the ship. But we don't know when the clock started ticking. Scotty says the ship has returned from her shakedown cruise, the length of which is unknown.
3) There's the stardate, 8454. The previous movie had 8031 to mark the start of the main body of the adventure, but the epilogue of our heroes receiving the E-A is undated. (We have no clear idea of what stardates in TOS mean, but we could just as well assume there are a thousand units per year, just as in TNG - because that would nicely match the TOS length of about five thousand SD units with the five-year mission. A difference of 450 units would then be about five and a half months.)
So, nothing really solid. But if it only took three weeks to redo the bridge, then we must accept it's very modular - either the entire room can be swapped whole, or then each console sector can be independently swapped for another, or for a turbolift station.
Timo Saloniemi