Generations is the only TNG film I didn't see the work print of, sadly. I was with Paramount in NY for 15 years starting in 1996, and an intern there prior to that in the late 80's and early 90's. Also saw a work print for ST VI, incomplete with temp VFX (could see the rod holding the bird of prey as it flew past) and other shots just in story board phase.
The prints we screened for exhibitors for FC, INS and NEM were pretty final cut prints.
I won't debate the veracity of the OP, it's really no big deal either way to me. I will share a personal story though of how SOME print mishaps do occur.
When Truman show opened, my office received a call from Roger Ebert's office wondering why the credits for the film were in FRENCH! He screened it at a Manhattan theater that was part of my territory. In a matter of minutes I was able to track the print, and realized that the last reels of that print were from a Canadian print that should have been recalled and replaced. This one slipped through, making it on screen and in public. I had the reels replaced by the end of the day, but I'm sure there are a lot of confused people out there on why Peter Wier chose to put the credits in French.