I think that really depends on the people involved and their "fighting style".
Throughout our 20+ years together, MrS and I have a BIG fight about once every 18 months - they are rare enough that they get names (usually based on something that happened during the fight - "The Jelly Donut Incident of 1997" "The Broken Chandelier Battle of 2008" etc.) - most of these end in laughter and reconciliation and we can't remember what started it. We have had about 3 "serious" fights in all that time - where wounds were uncovered that really needed to be addressed, so we addressed them.
Dude and I bicker and spat all the time (which makes MrS uncomfortable - that is not his style at all). We are both stubborn, bullheaded, intellectual-debate sorts - and these "discussions" can get rather heated. It's only when it devolves into condescending tones and sarcasm that MrS starts squirming and asks us to knock it off. Our "real" conflicts are sorted out with more serious and measured conversation - usually with an agenda and bullet points...
Lotus and I have yet to have any conflict between the two of us (and I don't know how that would even look...we tend to have more broad reaching conversations about life and conflict in general and our relationships with each of the boys).
Me: poly bi female, in an "open-but-not-looking" V-plus with -
MrS: hetero polyflexible male, live-in husband (24+ yrs)
Dude: hetero poly male, live-in boyfriend (5+ yrs) and MrS's BFF
SLeW: platonic girlfriend and BFF
Lotus: "it's complicated"
+ "others" = FBs, FWBs, lover-friends, platonic G/BFs, boytoys, etc.
My poly blogs here:
The Journey of JaneQSmythe
The Notebook of JaneQSmythe