These public unions plan their strikes months, even years in advance.
Right now, in any state, there are teacher's union reps planning the location of the next strike. The location will be a place that is largely trouble free but the purpose of the union is to force higher taxation and higher pay for already overpaid union workers. Even if everything is flowing nice and smooth in the school system in your state, those degenerates are planning a sneak attack.
I get the whole union thing for coalminers or steelworkers and even baseball players, but for public (government) workers?