I think that one of the challenges is that these losers can engage in meticulous planning, but not completely rational thought.
I'm sorry, but the ability to study and plan an attack IS rational thought. It's wrong, its evil, but it is rational thought. A complex, complicated task, thought out and performed cannot be considered "irrational thought", and that is one of the biggest "dis-services" we do to ourselves, the constant stating that that these evil acts are irrational and done by people who are "mentally ill".
Because, while in our opinion, its irrational to do such a thing, and therefore the actors MUST be mentally ill, saying that creates an impression that these people are not able to plan and perform complex actions, which is, clearly, NOT the case.
As to attacks on police stations, I think it's worthwhile to distinguish a difference between a mass shooting, and a deliberate attack on the police, which results in a mass shooting.
I think one needs to look at attacks on police in a slightly different light, because, unlike attacks on crowds of (presumably) unarmed people, the police are armed, and the attackers know this going in. HOW many, if any, attacks at police stations were NOT attacks against the police?? What I mean is, that if your object is just to shoot people these attackers don't go to police stations for that, they choose other places. But, if the object is to shoot police, then they go to where the police gather.
I don't put this in exactly the same class as a mass shooting at a mall, a church, a club, a concert or a political rally.