I have 2 doggy doors. One to a fenced area that they can use anytime. The other is in my deck screen door and is only open when I open the sliding glass door.
The dog doors I have purchased for regular doors, always come with a cover, so that you can chose to close off the dog flap when you don't want the dogs to use it. I generally only use this closure when there is a very windy rainstorm. I close it then or else the wind blows the rain in. For normal rainstorms, there is no problem.
My dogs sleep in my bedroom with me and my bedroom door is closed. So they aren't going out in the middle of the night. However I leave the dog door available all the time. The dogs go out whenever they need to. My big problem is that Merry loves to bark. She'll go outside for that purpose too.
Charleen and Cav's: Pippin (ruby male), Merry (b&t female), Luke (blenheim male) & Jolly (tri male puppy)