According to Evan Stark, one of the most respected and prolific domestic violence researchers in the US:
So what has happened is that because we have a law that focuses on discreet incidents of violence, and because the vast majority of domestic violence incidents are trivial from a criminal justice or medical standpoint, the vast majority of domestic violence arrests and cases result in absolutely no sanctions that are significant enough, or even approach significant enough, to inhibit subsequent domestic violence crimes. In other words, what we’ve done by turning domestic…by taking an incident specific approach to domestic violence is effectively to turn domestic violence into a second-class misdemeanor for which almost no one goes to jail. But in the 60 percent of the cases where I believe the pattern of violence is complemented by this extended pattern of intimidation, isolation and control, I believe a much more broad-based and fundamental crime needs to be identified and enforced.
Evan Stark
So yes,
every incident in the abuse dynamic, no matter how seemingly trivial, tells us about the pattern that led up to Gabby's murder. The violence
is the pattern, not the individual incidents. It also matters because there are those, even here, saying "Well, we just don't know for sure yet that Brian actually murdered her," etc. Establishing that the pattern fits the textbook DV pattern (which, as a researcher getting a PhD in this, I strongly believe it does) gives us some level of certainty that the trajectory of abuse led where it so often does--to the abuser murdering the target of the abuse.
Also important: If Brian put his hands around Gabby's neck as she seems to indicate, there is strong evidence that this was a predictably lethal situation. Strangulation is one of the strongest indicators of lethality (as many others have correctly posted about here) even had that not turned out to be Gabby's COD, which makes the hands-on-neck even more vital to understanding the eventual murder of Gabby.
Tools & Strategies for Assessing Danger or Risk of Lethality