"There's bodies in the streets. This place isn't free, not anymore!" x 8,000
One of the last main towns in Divinity OS2 had the most overwhelmingly annoying NPC dialogs, and yes- they repeat on 20-30 second intervals.
Coming from someone that knows nearly nothing about dev and coding- it really shouldn't be too hard to set some kind of counter to limit the frequency that it happens. Absolutely agreed, it's too much. Give them longer duration between spoken lines and ideally 2-3 lines to repeat. While that means more voiceline work, I would be content with simply hearing less of them or only hearing those lines upon arrival to the area.
Yes, I could spend less time at the vendor. Yes, I could turn down voice dialog audio levels. Yes, I could etc etc etc. Bottom line is: anything that forces you to adapt to the game out of annoyance is a poor design choice.