What I tend to see is the lead team, knowing they're in the lead, will back off a bit and play defensively, and/or assess the flow of battle, leaving 2nd and 3rd place to vie for points. Other times, one team refuses to back off the other (usually 2nd and 3rd, or 1st and 3rd, leaving 2nd free to creep ahead). And as mentioned, sometimes, people just don't notice the score.

There are those times too that people/teams who know each other clash, and it becomes a war of attrition and/or a battle for respect, lol.