I don't necessarily prioritize my preparations based on "the odds". If I did so, there would be no reason for me to carry a compass while hiking. The chances of getting lost in the Colorado drainages where I hike are miniscule (to get out - "walk downhill, and don't cross any high elevation ridges" - you don't need a compass for that). But I carry one anyways.

Preparing for a "campus shooting" is not specific to campus. It is also applicable for "department store shooting", "grocery store shooting", "movie theater fire", etc.

For anyone to say, "the odds are against this happening to me", while an accurate statement, is an incredibly dumb one. So my goal during one of these incidents will be to surround myself with as many "it won't happen to me's" as possible to serve as a human shield and diversion.