All that planning, and the perp is scoping out the scene of his premeditated rampage, because he(or maybe even she) goes there....daily. knows the layout, knows the game plan, could even know when the people's breaks are, when they take a dump, etc....
Alternatively, we can take mental health more seriously, and be proactive and less reactive.
Don't discount the fact that they look for soft targets. They are usually looking for power and not a fight. It would not stop all, but it would stop the majority.
As for the other part, I can only hope. This usually devolves into muh guns vs muh guns ban.