Clarification on Recommendations for Common App

So do I have this right? I invite recommenders through common app. Now when I assign them to a college, do they have to write a recommendation for each school or once they do it for one, the rec is saved in the system and I can send it to however many schools I want? All schools have the same policy on recommendations/school report minus the number required? Just making sure that if I want to apply for 5 schools, my teacher doesnt have to write 5 recommendations.