Hard to know exactly what they thought of stardates. The Motion Picture takes place during stardate 7412.6. The Wrath of Khan, 8130.4. Yet, they are close to a decade apart. The Search for Spock starts on 8210.3. The Voyage Home, 8390.
There are 180 units difference between The Search for Spock and the beginning of The Voyage Home.
180*2.7=486 days. Yet they were only on Vulcan for three months, and I can't imagine that the events of Search... took more than a few days.
Stardates for TOS are usually a wildly inaccurate way to judge time.
Exactly. Like I said, Stardates were always pretty arbitrary, least during TOS era.
The series Bible even says as much, more or less:
"Pick any combination of four numbers plus a percentage point [ed. note: tenths digit], use it as your story's stardate. For example, 1313.5 is twelve o'clock noon of one day and 1314.5 would be noon of the next day. Each percentage point is roughly equivalent to one-tenth of one day. The progression of stardates in your script should remain constant but don't worry about whether or not there is a progression from other scripts. Stardates are a mathematical formula which varies depending on location in the galaxy, velocity of travel, and other factors, can vary widely from episode to episode."
Again, Stardates were always meant to be ambiguous as at the time Roddenberry didn't want to nail down a specific time period for it.
It wasn't until TNG/DS9/Voyager era that the show runners began to pay attention and employ a chronological approach to them (well least after TNG Season 1, and even then there were issues from time to time across the various series and TNG era films in terms of Stardates not jiving).
But, one thing to note in that series Bible quote mwntions "Stardates are a mathematical formula which varies depending on location in the galaxy, velocity of travel, and other factors, can vary widely from episode to episode."
So location, warp speed, etc can apparently alter the Stardates, and thus chronologically placing episodes in order of Stardate alone is incorrect as well.
Have to say, for all the reboot films' faults, at least their calendar/Stardate system is logical and easy to follow (year and day, 2258.42, or February 11, 2258).