You have a family plan and take steps to follow that plan, I notice you did not state you go search immediately, but rather wait "to see"!
Depends on the situation. When I've heard noises outside, for example, I've grabbed my gun and investigated. Same if I heard noises in the house. Now if I heard the sound of my front door being kicked in and one or more people coming into my house, I would likely react differently. Like I said, I weigh each situation on a case by case basis.