I think there's been a positive change since Rugby Union scum engagements went from "Crouch-Touch-Pause-Engage" to "Crouch-Bind-Set". The initial contact is not as violent, and it would seem far fewer scrums are collapsing, especially on the point of engagement.

I don't have stats to back this up, but my general impression over the last couple of seasons is that less scrums require resetting.