I must say, by the way, I love these types of conversations. True Trekkies in perfect form right here, guys. We can almost rationalize ANYTHING.
Personally, I've never given much thought to the passage of time because TMP and TWOK are so fundamentally different from one another. I've often considered TWOK to be the TRUE first Star Trek film because the characters (with the exception of McCoy) felt so off
to me and the movie was so cold in its portrayal.
Sometimes however I think it does little service to Trek to seek out one specific or definitive explanation, in this case, because the two films are so different.