I think given the number of things that can happen with ~30% probability, there's probably something significant happening with ~30% probability at basically all times.

30% of the time it is all of the time.

Well, we're talking about elections. You have an election where there's a president, 30 or so governors, 33-34 senators, and 438 representatives. Say a total of 64 major offices, or 500 if you count the representatives. You'd expect a 30% chance to happen in 19 major races, or 150 races if you count the representatives.

So in an election, that happens all the time. It just doesn't always happen in the race for president.