When you use this dialogue transition as a cheap shortcut to lay out some exposition for me, I turn right into Alison Hendrix.
It’s such a bad technique that I lose confidence in the rest of your script. It tells me that for you, dialogue is how the reader finds out about the plot ahead of time, which is a fundamental structural failure.
As an example, I just read a first-act scene that loaded me with lots of explanations “disguised” as “banter”, which took a hard left turn into, “Speaking of (blank), are you going to (do that plot thing) today?”
I immediately put it down and wrote this post.
It is that bad, and it’s incredibly common in scripts that get a no in the first round. So, word to the wise.
Edited to add: This phrase is not a terrible thing in itself. It can be used for good. As in: “Speaking of 15-cubic-foot freezers, how’s your mom?”