Gene Roddenberry had a stringent rule when it came to line memorization

Gene Roddenberry had some set rules when it came to Star Trek, things that were simply not allowed in any episode, especially Star Trek: The Original Series. The one we all know well is "no personal conflict between the crew members," but there were others that made things a bit more challenging for the actors instead of the writers.

As shared by SlashFilm, one of them was relayed by Tom Wright, the actor who portrayed Tuvix on the Star Trek: Voyager episode of the same name. In 2014, Wright answered questions from the Reddit community about his time on Voyager, and though he felt like he'd reached the "big leagues" when he was cast in the role of Tuvix, he also discovered there was a strict tenet during filming.

"One of the major tenets was that not only should actors KNOW their lines but if they were to make a mistake, there would be no continuing the scene.
"

- Tom Wright

What this meant was that actors couldn't just flub their lines, correct their mistake, and move on during the scene. Instead, the entire scene would be shot over from the beginning. Wright didn't have an issue with the rule as he was trained in the theater, and that's how things were done there. But to those actors who had to memorize line after line of technobabble, can you imagine how difficult it was for them and how much pressure it put on them?

Restarting a scene would take even more time and could potentially add to production costs. Who would want to be responsible for making the episode go over budget? It's no wonder that many of the actors still know their lines even though they last said them twenty plus years ago. They learned them well to avoid having to reshoot an entire scene.