In college theatre, especially with a faculty director, the lines get a little blurry. Its hard assert yourself like that when you're in a position where the person you're questioning has grading power. Was the LD a student or a professional?
Recently, I did a grad school showcase in NYC, and we were horribly behind because our space was terrible, so the LD couldn't be there on the afternoon before we opened. He knew that things were going to come up in that rehearsal that the two directors would want adjusted, so we set it that as soon as the rehearsal was over, I would pull out my cell and call him, describe the adjustments (with cues numbers ready), and he'd talk me through programming the change. The director would look at it, okay it, and we'd move on. Professionally, this is closest I've come to the director making changes on their own, but it was with the consent of the LD, and it was due to circumstances beyond all of their control.
As for minimal changes after tech, I disagree. I've certainly had shows where my LD is giving me completely new cues for sequences up through the final preview. Granted, after tech MOST changes are in intensity, most of the LDs I've worked with will throw in new cues here and there, link cues that were previously seperate, etc. for as long as they can.