Fair enough. But what about here:
Cassandra: "Enough power poured into that mark..."
Cullen: "...might destroy us all."
Cullen should have been MUCH more forceful and quick to cut her off. Instead, it was such an awkward transition I wondered whether Cassandra was lyrium addled...
Here's another example:
Cullen: "The Templars could suppress the Breach, weaken it so..."
(Inquisitor [thinking] "So... What? Were you going to finish that thought?")
Leliana [Oops, I missed my cue!] "...Pure speculation!"
Honestly, most of that dialogue was cringeworthy.
But I suppose this is off topic.
Except that people actually do talk like this. A lot. An ACTUAL interrupted conversation is basically impossible to recreate via acting because the interrupted person usually continues speaking (sometimes at length) and may even raise their voice while doing so, so instead of a nice clean "I cut you off" what you hear is a jumble of two people talking at the same time--which you don't want in a play or similar where the audience is actually supposed to, you know, UNDERSTAND the dialog. When you get a genuine interruption where the first speaker actually cuts off, it generally turns into a complex little diversion that, in fiction, is a giant waste of time and rarely portrayed because it accomplishes nothing except characterization and not much at that. The perfect "I will finish your sentence now" interruption is almost entirely an artifice of acting because it really only works if the person speaking KNOWS that they're supposed to STOP talking when you start.
If a group of people know each other and share a lot of the same information, this kind of tailing-off conversation is actually super-common. Cassandra, Cullen, Leliana and Josephine have already discussed this stuff--they're not interrupting each other, they're filling in the bits that other people have left as given for the Inquisitor. Leliana pauses because she's searching for an appropriately neutral term. Cullen pauses because he doesn't KNOW what the results will be, so he can't really describe them off the cuff. It sounds EXACTLY like how my gaming group explains the situation to a new player--someone will start speaking, they'll hesitate over the next bit, and then someone else will grab the thread and continue.
Now, was it what they were going for? Who knows. But it's actually a pretty well-put-together discussion if you are a student of how people ACTUALLY speak instead of how they're often written to speak in plays, movies, etc. Real conversations contain lots of dead time, hesitations, backtracking, etc. If you're going for realism, that is GOOD writing, not bad timing.