Nobody can answer that. Abuse can be low intensity, spread across large period of time or intense 1-off event and resulting damage can be similar. Spread across whole lifetimes till the point of experiment.

Extremely individual reactions, what makes one tougher breaks another completely and permanently, and everything in between.

I'd say everybody experienced some sort and level of abuse, typical school bullies (which were usually also bullied somehow, hence the behavior).

Back in the course of human evolution there must at some point have been mammals who were not yet riding on the dysfunctional cycle of violence. That means the natural rate must be non-zero, at least, or else the cycle would have no starting momentum.