I remember a "Starlog" interview where she was asked about her ST IV rank. She recalled a discussion she had with the wardrobe people. She told them "I was a Chief" in TMP and mentioned that a fan had told her that the insignia was being sold by Lincoln Enterprises as a "petty officer pin" so someone on set said, "So now you're a "Chief Petty Officer"! Her uniform in ST III had "Commander" pins on it, but that scene was shot at ILM and she simply wore a uniform that fit her. It seems that rank carried over to the ST IV credits, despite her ST IV uniform and pins.
So much that is seen on screen is contradictory. My take is: 2266 TOS: Petty Officer First Class 2273 TMP: Chief Petty Officer 2285 STIII: Undercover Starfleet Intelligence - (the mystery of who ate Admiral Catwright's sausage roll) 2286 STIV: Master Chief 2289: Qualified as Ensign 2293: Lt(jg) on Excelsior 2294: Promoted to Lt 2295: Promoted to Lt-Commander in time for World Enough & Time
During my many watchings of TWOK I found the woman in the center's backside very nice to look at (she's always in the bridge facing monitors). Thanks to memory-alpha I learned her name. But I forgot it. And I don't want to know what her backside looks like nowadays, 40 years later.