Speaking reasonably though, the length of time has no bearing on this argument. By that logic a 3 day poker tournament would be a sport, but a 10 hour poker tournament would not.

If 3 day math exams were in fact devised and executed, would they then be considered sport?

If they followed the requirements of a sport, yes. Lets take a look at the definition of a sport posted above: An activity involving physical exertion and skill in which an individual or team competes against another or other.

Let’s now break it down, an activity? Yes
An activity involving physical exertion? This implies the use of energy by the body to participate in the activity. In poker long days of play can do so very easily, that’s why they call it a young man’s game.
Skill: Depends on the test, but in poker you should have some level of skill to make it through the waves of hands.

So it depends on the test itself, not just the amount of time required.

mma is a collection of many sports/martial arts