You are assuming that each school shooting is in a separate district in the calculation. That is not necessarily the case, especially with some large school district serving many more students than a small rural district.

But I agree with you that it affects the school and community deeply, even in surrounding communities. I live in Texas, and the whole state was deeply affected after Uvalde. A relative's school got evacuated a few weeks later out of what happened to be a false alarm, with the relative forced to exit the school hands above their head to show they didn't have a gun. They were on the complete other side of the state, probably like a 6 hour drive away.