I think I hear about a school shooting about once every two or three months. And, I believe underreporting at a national level paired with myself not having time to keep up means that I hear about roughly one in every hundred shootings.
Typically there's about 180 days of school per year.
Crunching some vague math, my guess seems preposterous: ~340 school shootings in 2024. That's almost two per day. But, the more I thought about it the less preposterous it seemed.
TL;DR - My guess is a seemingly preposterous 340 school shootings in 2024, or almost 2 per school day.