I've been told more than once by reviewers to lose words like "Just then"
Guilty as charged, so I guess I should weigh in.
Disclaimer: I overuse "just", "then", and "so". I've trained myself to spot them on 2nd drafts.
Joseph terminated the feed. “They’re insane..."
Just then, an explosion rocked the prison
As Deckland says, this "Just then" replaces the actual shortcut word "Coincidentally". It allows two dissimilar events to occur without build up. This is valid in rare or high-stakes situations. Used elsewhere, it's a shortcut.
Using it in an early draft is great. Now you can search it. Every time you find it, ping yourself with another -coincidence-
I recently caught myself having characters walk in on conversations at opportune moments: "... as if summoned, X rounded the corner...". Next draft, I'll be able to solve that by introducing X to the scene earlier, or mention X's imminent arrival at the start of Y's conversation.
Joseph terminated the feed. “They’re insane! They just put the fate of humanity solely in the hands of Emperor Bastardus!”
An explosion rocked the prison. Everyone ran out of their cells and looked for the source. A siren began to wail.
I don't have a suggestion for this one. Sometimes, "Just then" is really the perfect phrase. If this was Star Trek, it would be:
Joseph terminated the feed. “They’re insane! They just put the fate of humanity solely in the hands of Emperor Bastardus!”
[Cut scene to unrelated holodeck substory. Picard at a sleazy bar while Data learns to tell standup. Data gains some new insight or reveals a character growth.]
An explosion rocked the holodeck and the images flickered. Picard ran out and looked for the source. A siren began to wail.