Hey, I looked into this too! And I came to the conclusion that it's completely true.

The movie she mentioned in the anecdote was I Want To Believe. Here is the actual scanned screenplay, rather than re-typed:

https://lvei.net/wp-content/uploads/script-de-prod/The-X-Fil...

Just scroll through and look. In almost every paragraph or dialogue block, the last line ends very close to the right margin. Pretty much the only places that doesn't happen is when there's a single short line of dialogue by itself, meaning it doesn't wrap to a second line.

Looking through scripts on Boggsfiles, it's much more inconsistent, but it does happen, and perhaps more frequently in the later seasons. Here's one, from season 9; take a look at page 10 (page 13 in the PDF) for example, but it really happens throughout.

https://drive.google.com/file/d/1dlnc2prPVgPLN4CQSiMQMvD2VSl...