In Steve Muhlberger's Formal Combats in the Fourteenth Century, he discusses particular instances of combat that were sufficiently formal not to just be two guys getting into a fight, yet weren't exactly part of warfare or battles.

Given the particularity of the examples Muhlberger uses, it seems to me that it wasn't something that happened as commonly as you might see in Arthurian romance, but that formal combat sparked by personal or trivial motives did happen.

On mobile, so apologies for any typos/formatting errors.

One of the real difficulties of answering this is source based, minor scrapes between knights and lords in the High Middle Ages do not seem to be particularly prevalent in narrative sources and 'amicable' scraps would not make it into legal sources as they would not end in enmity requiring court resolution - were they following the topoi of romantic sources. Does this mean they definitely didn't happen - no - as, albeit later, incidents demonstrate there were cases of staged challenges (halsitudes consisting of pas d'armes) on bridges of illustrate in the fourteenth- and fifteenth-centuries.

These games were violent in the same sense modern contact-sports are violent. Harm might come but was not the intention, but they seem to have been cases of life imitating art as the trope existed well before these are regularly documented. They are, similarly to the later tournament, a highly stylised form of conflict with little of the social and political implications of a medieval duel.

Medieval Romance's chief influences, in this regard, were the chanson de geste which, in turn drew influence from earlier Heroic stories with central characters more similar to Beowulf. The chanson de geste typically were set in decentralised and quasi-anarchic lands where roads, bridges, towns, and even cities were dominated by jealous robber-barons and enforcers who defended the right to ingress on their roads, bridges, or towns by force. One can see echoes of this type of society, albeit more regulated by pragmatic economic concerns, in southern France. Here lords would alienate the rights to tolls of key roads sometimes to large groups of knights which they would essentially police and use to extract their living from (versus manorial structures in England or Normandy). What we also note in this society are numerous vicious feuds and private wars which this type of societal structure might have engendered.

Such was not the case in England and the periods of anarchic instability were heavily regulated by powerful local magnates. The violence which erupted during Stephen, John, and Henry III's reigns were not similar in content to the ritualised chivalric violence of many Romances, they were civil wars and in many cases the etiquette on show went out the window entirely.

There is no doubt that the prevalence with which these conflicts arise in Romances pales in comparison to the reality. Never forget that these were meant to be entertaining and educational stories and that contemporary audiences were able to discern that.

In reality, if you violently oppress or attack persons who have the capacity to fight back then what you will cause is a conflict which can rapidly escalate and result in bouts of private warfare or, at worse, feud. These will be what survives in historical record, not the smaller incidents of violence and were what the stylised forms of combat in part resolved - allowing expressions of violence and laudable demonstration of prowess within acceptable boundaries (even if those boundaries were as loose as 'try not to kill anyone' or, as David Crouch puts it, 'it's a shame if someone dies').