When authors will use any word other than "said."

I've been listening to the first Expanse book on and off recently, and one thing I noticed is almost all the dialog is almost literally just: "Holden said 'blank,' and then Naomi said 'blank.' 'blank,' said Alex." Tbh it's kind of boring to listen to. Sometimes you need to break up the monotony and use a synonym. Plus it makes you sound smarter.