Yeah, I think most people draw headshots all the time because they think it's the fastest way to get the panel done. But I've come here with a few life hacks to make quick panels during long conversations that doesn't rely on 3/4 headshots!
The first life hack- well, this one may need you to get decently good at drawing the human body, and certain body parts first, but it'll be a good long-term investment, I assure you! Basically, the "hack" is to break up strings of headshots with close-ups of hands, feet, etc. of what the character is doing. I usually use hands because they are one of the most expressive body parts, so sometimes I'll use it to imply an emotion the character is feeling, as opposed to just showing their face having that expression. Like in the example below with the hands clenching.
While you may think it takes longer to draw things like hands, and it may be true if you have trouble drawing them, once you get the hang of drawing body parts like hands, you'll realize that usually there's a lot less need to go into a lot of detail with hands as opposed to drawing a head. With a headshot, you gotta make sure you're drawing the hair and eyes, sometimes mouth and nose, correctly, and depending on your style, you might be needing to put a lot of detail in those body parts! Meanwhile, for hands, the most you'll probably need to worry about detailing is the fingers, and maybe the fingernails if you draw that, and if you wanna go really detailed, maybe the wrinkles on the hands. If you color, you probably need a minimum of 3 colors to fill in with hair, skin, and eyes. For hands, you'll need a minimum of 1 color, which is just the skin for the hands.
Of course, a lot of the things mentioned above is a bit situational, maybe you have really detailed sleeves on the characters so it might be less time-consuming to draw the face in those situations XD But from my experience drawing a "hand panel" feels a lot faster than drawing a "face panel" once you start getting the hang of hands
But anyways! What if you don't want to draw those pesky hands or body parts. You're just not confident in them right now! Well, here's life hack #2: inject panels of objects that relate to the subject of the conversation. They can be close-ups of things in the environment, or just objects that directly relate to the conversation. Like in here, I used a panel of some papers during a mention of "reports" in the conversation. Drawing paper is way faster than drawing a face! >:0 (and also presenting you, legs walking up the stairs as another method to avoid drawing faces)
I also think you can use the "focus on things in the environment" sometime as a neat foreshadowing trick.
Anyways, I don't know how well these "life hacks" actually apply, but I'm just giving my two cents of my experience and what methods I've used to make speedy panels without being too overly reliant on headshots.
I actually try my best not to use too many panels of just drawing headshots during conversations lately. The thing is, I'd either have to draw each face separately and make them look consistent across all panels, or copy paste the faces for every panel. The latter method is indeed super fast, but if I do it too much the readers are gonna notice!! 
